

A176253


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


9



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
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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



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



KEYWORD

nonn,base


AUTHOR



STATUS

approved



