

A072509


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


2



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, 19, 19, 20, 21, 22, 22, 22, 23, 23, 23, 23, 26, 27, 27, 27, 29, 29, 30, 30, 31, 31, 31, 31, 32, 34, 35, 35, 36, 37, 38, 38, 38, 39, 39, 39, 39, 42, 42, 43, 43, 45, 45, 46, 46, 47, 47
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OFFSET

0,1


COMMENTS

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


LINKS

Robert Israel, Table of n, a(n) for n = 0..10000


MAPLE

N:= 100: m:= 0:
A:= Array(0..N):
A[0]:= 2:
for i from 0 while m <= N do
for j in [1, 2, 8, 19, 22, 28, 41, 59] do
m:= ilog10(combinat:fibonacci(60*i+j))+1;
if m > N then break fi;
A[m..N]:= A[m..N]+1;
od od:
convert(A, list); # Robert Israel, May 14 2018


MATHEMATICA

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 *)


CROSSREFS

Different from A073550. Cf. A072353, A072675.
Sequence in context: A030585 A030565 A174231 * A269362 A321695 A197432
Adjacent sequences: A072506 A072507 A072508 * A072510 A072511 A072512


KEYWORD

base,easy,nonn


AUTHOR

Vladeta Jovovic, Aug 23 2002


STATUS

approved



