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

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

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