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

Author

Carmine Suriano, Apr 13 2010

Keywords

• nonn
• base

Comments

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

Examples

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

Crossrefs

Cf. A000045.

Programs

Magma

[n: n in [1..30000] | not 5 in Intseq(Fibonacci(n))]; // Vincenzo Librandi, May 10 2019

Mathematica

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

PARI

isok(n) = {digs = digits(fibonacci(n)); for (i = 1, #digs, if (digs[i] == 5, return (0));); return (1);} \\ Michel Marcus, Sep 02 2013