Is it a super-prime?

Question

Background

A super-prime is a prime number whose index in the list of all primes is also prime. The sequence looks like this:

3, 5, 11, 17, 31, 41, 59, 67, 83, 109, 127, 157, 179, 191, ...

This is sequence A006450 in the OEIS.

Challenge

Given a positive integer, determine whether it is a super-prime.

Test Cases

2: false
3: true
4: false
5: true
7: false
11: true
13: false
17: true
709: true
851: false
991: true

Scoring

This is code-golf, so the shortest answer in each language wins.

Answer 1

Jelly, 5 bytes

ÆRÆNċ

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How it works

ÆRÆNċ  Main link. Argument: n

ÆR     Prime range; yield the array of all primes up to n.
  ÆN   N-th prime; for each p in the result, yield the p-th prime.
    ċ  Count the occurrences of n.

Answer 2

Mathematica, 26 23 bytes

Thanks to user202729 for saving 3 bytes.

PrimeQ/@(#&&PrimePi@#)&

This makes use of the fact that Mathematica leaves most nonsensical expressions unevaluated (in this case, the logical And of two numbers) and Map can be applied to any expression, not just lists. So we compute the And of the input and its prime index, which just remains like that, and then we Map the primality test over this expression which turns the two operands of the And into booleans, such that the And can then be evaluated.

Answer 3

Jelly, 6 bytes

ÆRi³ÆP

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Uses the same technique as my Japt answer: Generate the primes up to n, get the index of n in that list, and check that for primality. If n itself is not prime, the index is 0, which is also not prime, so 0 is returned anyway.

Answer 4

Japt, 13 11 bytes

õ fj bU Ä j

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Explanation

This is actually very straight-forward, unlike my original submission:

 õ fj bU Ä  j    
Uõ fj bU +1 j    Ungolfed
                 Implicit: U = input integer
Uõ               Generate the range [1..U].
   fj            Take only the items that are prime.
      bU         Take the (0-indexed) index of U in this list (-1 if it doesn't exist).
         +1 j    Add 1 and check for primality.
                 This is true iff U is at a prime index in the infinite list of primes.
                 Implicit: output result of last expression

Answer 5

Python 3, 104 97 93 bytes

p=lambda m:(m>1)*all(m%x for x in range(2,m))
f=lambda n:p(n)*p(len([*filter(p,range(n+1))]))

Returns 0/1, at most 4 bytes longer if it has to be True/False.

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Answer 6

Jelly, 7 bytes

ÆCÆPaÆP

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ÆC counts the number of primes less than or equal to the input (so, if the input is the nth prime, it returns n). Then ÆP tests this index for primality. Finally, a does a logical AND between this result and ÆP (primality test) of the original input.

Answer 7

Haskell, 62 bytes

p x=2==sum[1|0<-mod x<$>[1..x]]
f x=p$sum[1|y<-[1..x],p y,p x]

Try it online! Usage: f 991 yields True.

Answer 8

Pyth, 12 bytes

&P_QP_smP_dS

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Explanation

&P_QP_smP_dS
                Implicit input
       mP_dS    Primality of all numbers from 1 to N
      s         Sum of terms (equal to number of primes ≤ N)
    P_          Are both that number
&P_Q            and N prime?

Answer 9

05AB1E, 6 bytes

ÝØ<Øså

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Explanation

ÝØ<Øså
Ý      # Push range from 0 to input
 Ø     # Push nth prime number (vectorized over the array)
  <    # Decrement each element by one (vectorized)
   Ø   # Push nth prime number again
    s  # swap top items of stack (gets input)
     å # Is the input in the list?

Answer 10

Pyke, 8 bytes

sI~p>@hs

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s        -  is_prime(input)
 I~p>@hs - if ^:
  ~p>    -    first_n_primes(input)
     @   -    ^.index(input)
      h  -   ^+1
       s -  is_prime(^)

Answer 11

Perl 6, 46 bytes

{$/=&is-prime;all($_∈*,$/)([grep $/,1..$_])}

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Answer 12

Mathematica, 35 29 bytes

P=Prime;!P@P@Range@#~FreeQ~#&

-6 bytes from @MartinEnder

Answer 13

QBIC, 33 bytes

~µ:||\_x0]{p=p-µq|~q=a|_xµp]q=q+1

Explanation

~   |   IF   ....  THEN (do nothing)
  :         the number 'a' (read from cmd line) 
 µ |        is Prime
\_x0        ELSE (non-primes) quit, printing 0
]           END IF
{           DO
            In this next bit, q is raised by 1 every loop, and tested for primality. 
            p keeps track of how may primes we've seen (but does so negatively)
    µq|     test q for primality (-1 if so, 0 if not)
p=p-        and subtract that result from p (at the start of QBIC: q = 1, p = 0)
~q=a|       IF q == a
_xµp        QUIT, and print the prime-test over p (note that -3 is as prime as 3 is)
]           END IF
q=q+1       Reaise q and run again.

Answer 14

Haskell, 121 bytes

f=filter
p x=2==(length$f(\a->mod(x)a==0)[1..x])
s=map(\(_,x)->x)$f(\(x,_)->p x)$zip[1..]$f(p)[2..]
r x=x`elem`(take x s)

Answer 15

Positron, 148 bytes

x=#(input@@)a=function{p=1;k=$1==2;f=2;while(f<$1)do{p=p*$1%f;k=1;f=f+1};return p*k}r=1;i=2;while(i<x)do{if(a@i)then{r=r+1}i=i+1}print@((a@x*a@r)>0)

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Answer 16

Pari/GP, 31 bytes

n->(p=isprime)(n)*p(primepi(n))

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Answer 17

Matlab, 36 34 bytes

Saved 2 bytes thanks to Tom Carpenter.

A very naive implementation using built-in functions:

isprime(x)&isprime(nzz(primes(x)))

Answer 18

Python 2, 89 bytes

def a(n):
 r=[2];x=2
 while x<n:x+=1;r+=[x]*all(x%i for i in r)
 return{n,len(r)}<=set(r)

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Constructs r, the list of primes <= n; if n is prime, then n is the len(r)'th prime. So n is a super prime iff n in r and len(r) in r.

Answer 19

Python 2, 79 bytes

n=input()
s={2};p=i=1
while i<n:
 p*=i;i+=1
 if p*p%i:s|={i}
print{n,len(s)}<=s

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Answer 20

Julia 0.6, 61 bytes

return 1 if x is a super-prime, 0 otherwise.

without using an isprime-kind function.

x->a=[0,1];for i=3:x push!(a,0∉i%(2:i-1))end;a[sum(a)]&a[x]