A176253 Indices n corresponding to Fibonacci numbers Fib(n) whose decimal expansion does not contain the digit "5".

1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 19, 21, 22, 24, 26, 27, 28, 30, 31, 32, 38, 42, 43, 44, 45, 46, 49, 68, 69, 78, 79, 81, 86, 88, 89, 90, 94, 97, 102, 116, 117, 137, 161, 164, 285

Offset

1,2

Comments

Probability that a Fibonacci number Fib(n) (expressed in usual decimal base) contains no digit 5 approaches zero as n goes to infinity.

Links

Table of n, a(n) for n=1..49.

Example

For n=5 a(5)=6 since fib(6)=8 is the 5th Fibonacci containing no 5s (1,1,2,3,4,8,...).

Mathematica

Select[Range[1, 300], DigitCount[Fibonacci[#], 10, 5]==0&] (* Vincenzo Librandi, May 10 2019 *)

Prog

(PARI) isok(n) = {digs = digits(fibonacci(n)); for (i = 1, #digs, if (digs[i] == 5, return (0)); ); return (1); } \\ Michel Marcus, Sep 02 2013
(Magma) [n: n in [1..30000] | not 5 in Intseq(Fibonacci(n))]; // Vincenzo Librandi, May 10 2019

Crossrefs

Cf. A000045.

Sequence in context: A244219 A039258 A187968 * A277644 A039199 A172269

Adjacent sequences: A176250 A176251 A176252 * A176254 A176255 A176256

Keyword

nonn,base

Author

Carmine Suriano, Apr 13 2010

Status

approved