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A176253 Indices n corresponding to Fibonacci numbers Fib(n) whose decimal expansion does not contain the digit "5". 9

%I #12 Sep 08 2022 08:45:52

%S 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,

%T 42,43,44,45,46,49,68,69,78,79,81,86,88,89,90,94,97,102,116,117,137,

%U 161,164,285

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

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

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

%t Select[Range[1, 300], DigitCount[Fibonacci[#], 10, 5]==0&] (* _Vincenzo Librandi_, May 10 2019 *)

%o (PARI) isok(n) = {digs = digits(fibonacci(n)); for (i = 1, #digs, if (digs[i] == 5, return (0));); return (1);} \\ _Michel Marcus_, Sep 02 2013

%o (Magma) [n: n in [1..30000] | not 5 in Intseq(Fibonacci(n))]; // _Vincenzo Librandi_, May 10 2019

%Y Cf. A000045.

%K nonn,base

%O 1,2

%A _Carmine Suriano_, Apr 13 2010

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Last modified March 29 09:59 EDT 2024. Contains 371268 sequences. (Running on oeis4.)