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A072509 Number of Fibonacci numbers F(k) <= 10^n which end in 1.

%I A072509 #12 May 15 2018 03:01:00
%S A072509 2,2,3,3,4,5,6,6,6,7,7,7,8,10,11,11,11,13,13,14,14,15,15,15,15,17,18,
%T A072509 19,19,20,21,22,22,22,23,23,23,23,26,27,27,27,29,29,30,30,31,31,31,31,
%U A072509 32,34,35,35,36,37,38,38,38,39,39,39,39,42,42,43,43,45,45,46,46,47,47
%N A072509 Number of Fibonacci numbers F(k) <= 10^n which end in 1.
%C A072509 Note that F(k) ends in 1 if and only if k == 1, 2, 8, 19, 22, 28, 41, or 59 (mod 60). - _Robert Israel_, May 14 2018
%H A072509 Robert Israel, <a href="/A072509/b072509.txt">Table of n, a(n) for n = 0..10000</a>
%p A072509 N:= 100: m:= 0:
%p A072509 A:= Array(0..N):
%p A072509 A[0]:= 2:
%p A072509 for i from 0 while m <= N do
%p A072509   for j in [1, 2, 8, 19, 22, 28, 41, 59] do
%p A072509     m:= ilog10(combinat:-fibonacci(60*i+j))+1;
%p A072509     if m > N then break fi;
%p A072509     A[m..N]:= A[m..N]+1;
%p A072509 od od:
%p A072509 convert(A,list); # _Robert Israel_, May 14 2018
%t A072509 With[{s = Array[Fibonacci, 350]}, Table[Count[TakeWhile[s, # <= 10^n &], _?(Mod[#, 10] == 1 &)], {n, 0, IntegerLength@ Max@ s}] ] (* _Michael De Vlieger_, May 14 2018 *)
%Y A072509 Different from A073550. Cf. A072353, A072675.
%K A072509 base,easy,nonn
%O A072509 0,1
%A A072509 _Vladeta Jovovic_, Aug 23 2002