Have you learned your fib-abc?

Question

I don't like numbers, but I do like the Fibonacci sequence. I'm sure we could work something out.

Please read one integer n from STDIN and output the nth Fibonacci number in base 26 (abcdefghijklmnopqrstuvwxyz instead of 0123456789) to STDOUT.

The first Fibonacci number is 0. The second one is 1. The nth fibonacci number is the sum of the n-2nd and n-1st Fibonacci numbers.

First 32 fib-abc numbers:

fib(0) = a
fib(1) = b
fib(2) = b
fib(3) = c
fib(4) = d
fib(5) = f
fib(6) = i
fib(7) = n
fib(8) = v
fib(9) = bi
fib(10) = cd
fib(11) = dl
fib(12) = fo
fib(13) = iz
fib(14) = on
fib(15) = xm
fib(16) = blz
fib(17) = cjl
fib(18) = dvk
fib(19) = gev
fib(20) = kaf
fib(21) = qfa
fib(22) = baff
fib(23) = bqkf
fib(24) = cqpk
fib(25) = egzp
fib(26) = gxoz
fib(27) = leoo
fib(28) = scdn
fib(29) = bdgsb
fib(30) = bvivo
fib(31) = cypnp

This is code golf, so shortest code in bytes wins!

Answer 1

CJam, 18 bytes

UXri{_@+}*;26b'af+

Try it online in the CJam interpreter.

How it works

UX    e# Push 0 and 1.
ri{   e# Read an integer and execute the loop that many times.
  _   e#   Push a copy the topmost integer.
  @   e#   Rotate the bottom-most integer on top of the stack.
  +   e#   Pop the two topmost integers and push their sum.
}*    e#
;     e# Discard the topmost integer from the stack.
26b   e# Convert the remaining integer to base 26.
'af+  e# Add the character 'a' to each base-26 digit.

Answer 2

TeaScript, 34 bytes 37 51 54

TeaScript is JavaScript for golfing. It also brings ES2015 features to the average browser.

F(x)b(26)l(#C(lc()+(l<'a'?49:10)))

Try it online

Explanation

          // x is the input
F(x)      // Fibonacci from input
.b(26)    // To Base-26 string but with 0-9, a-p
          // instead of a-z, to fix this...
.l(#      // Loops through each char
   C(          // Charcode from...
       l.c()+  // Charcode from char
       (l<'a'? // If number
           49  // Add 49 to char code
          :10  // Else add 10
       )
   )
)

_{*This answer is non-competing}

Answer 3

Mathematica, 67 61 bytes

Print[""<>Alphabet[][[Fibonacci@Input[]~IntegerDigits~26+1]]]

Calculates f(1000000) in about 51 milliseconds.

Answer 4

Simplex v.0.6, 35 bytes

Sometimes I sigh and think, "Is this even worth submitting? It doesn't win, so why bother?" In response, I think, "Heck. It was fun. Besides, this is really fancied-up brainf*** anyhow. Not too shabby."

5_*Ij1~SRpRi@T[Uj&ERp]pSR5_Vj26@pWo
5_                                  ~~ sqrt(5)
  *                                 ~~ copy to next byte, move right
   I                                ~~ increment [sqrt(5),sqrt(5)+1]
    j1                              ~~ insert a new cell and set it to one 
                                    ~~ [sqrt(5),1,sqrt(5)+1]
      ~                             ~~ switch the previous with the current byte
                                    ~~ [1,sqrt(5),sqrt(5)+1]
       S                            ~~ perform subtraction [1-sqrt(5),0,sqrt(5)+1]
        Rp                          ~~ remove next cell [1-sqrt(5),sqrt(5)+1]
          Ri@                       ~~ take numeric input (n) into register
             T[      ]              ~~ applies the following to every cell
               U                    ~~ halves the current cell
                j&                  ~~ dumps and restores the value to the register
                  ERp               ~~ raises cell to the nth power, remove cell made
                      p             ~~ remove last cell
                       S            ~~ subtract the two values
                        R5_         ~~ goes right and sets sqrt(5)
                           V        ~~ divides the prev. two cells
                            j       ~~ inserts new cell
                             26@    ~~ puts 26 into the register
                                p   ~~ removes cell
                                 Wo ~~ converts the current to base 26 and outputs as number

Answer 5

Pyth, 17 bytes

s@LGjhu,eGsGQU2lG

Try it online.

Answer 6

Minkolang 0.9, 40 bytes

10n[0c+r]$x'26'r(d0c%1G0c:d$)xrx("a"+O).

Try it here.

Explanation

10n[0c+r]                                   Calculates f(n) where n is taken from input
         $x'26'r                            Dumps the addend I don't need and pushes a 26
                (d0c%1G0c:d$)               Base-encodes f(n) in base 26
                             xrx            Dumps the 0, reverses, dumps the 26
                                ("a"+O).    Outputs the letters

Answer 7

Python 2.7, 82 bytes

a=0
b=1
s=''
exec"a,b=b,a+b;"*input()
while a:s=chr(a%26+97)+s;a/=26
print s or'a'

Answer 8

Haskell, 114 chars.

It is unexpectedly long. Any help welcome. Previously found a bug for fib(0)

f=scanl(+)0$1:f
k 0=[]
k x=k(x`div`26)++[toEnum$97+x`mod`26]
l 0=0
l x=k x
main=interact$l.(f!!).read.head.lines

f is infinite list of fibonacci. toEnum is same with chr, except that former doesn't need to import Data.Char.

Answer 9

Ruby, 67 bytes

a,b=0,1
gets.to_i.times{a,b=b,a+b}
puts a.to_s(26).tr"0-9a-p","a-z"

Answer 10

Matlab, 133 bytes

n=input('');if n<2,y=n;else
f=0;g=1;for k=2:n
h=f+g;f=g;g=h;end
y=fix(mod(g./26.^(fix(log(g)/log(26)):-1:0),26));end
disp(char(y+97))

Answer 11

Ruby, 125 bytes

Not gonna win any time soon, but it was fun & my first code golf :')

def f(n);n<3?(n>0?1:0):f(n-1)+f(n-2);end
def a(s);s.bytes.map{|n|n<58?n+49:n+10}.pack("C*");end
puts a(f(gets.to_i).to_s(26))

First line is a function to compute fibonacci, second converts from Ruby's built-in base 26 encoding (0-9 then a-p) into a-z encoding, third gets a line from STDIN and runs it through both.

Answer 12

Python 2, 112 bytes

n=input()
if n<1:print'a';exit()
a,f=0,1
while n>1:a,f,n=f,a+f,n-1
r=''
while f:r,f=chr(f%26+97)+r,f//26
print r

Try it online.