A072912 Number of Fibonacci numbers F(k) <= 10^n which end in 0.

1, 1, 1, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 18, 18, 19, 19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25

Offset

0,4

Links

Table of n, a(n) for n=0..77.

Formula

a(n) = ceiling(n*log(10)/(15*log(phi))) +0 or +1.

Example

a(2)=6 because there are 6 Fibonacci numbers F(k) <= 10^2 which end in 0.

Prog

(PARI) a(n) = (sum(i=0, ceil(n*log(10)/log((1+sqrt(5))/2)), if(fibonacci(i)%10+1+sign(fibonacci(i)-10^n), 0, 1)))

Crossrefs

Different from A002280.

Cf. A008597, A214855.

Sequence in context: A194920 A327440 A285588 * A025786 A085886 A088676

Adjacent sequences: A072909 A072910 A072911 * A072913 A072914 A072915

Keyword

base,nonn

Author

Shyam Sunder Gupta and Benoit Cloitre, Aug 15 2002

Status

approved