A079690 Number of 5's in n!.

0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 1, 0, 1, 0, 2, 0, 3, 3, 2, 2, 2, 4, 3, 1, 2, 2, 2, 2, 5, 1, 2, 5, 6, 5, 7, 5, 5, 8, 5, 6, 5, 2, 4, 7, 3, 3, 11, 5, 6, 5, 5, 3, 7, 6, 4, 7, 10, 3, 7, 8, 5, 10, 7, 3, 7, 13, 9, 10, 6, 9, 7, 14, 13, 1, 12, 8, 13, 13, 11, 10, 10, 12, 17, 17, 14, 15, 12

Offset: 0

Author

Cino Hilliard, Jan 31 2003

Keywords

• nonn
• base
• easy

Links

• Seiichi Manyama, Table of n, a(n) for n = 0..10000
• Index entries for sequences related to factorial numbers.

Crossrefs

Cf. A027869, A079714.

Cf. A000142, A137579, A137580.

Programs

Mathematica

DigitCount[#,10,5]&/@(Range[0,100]!) (* Harvey P. Dale, Sep 17 2016 *)

Formula

a(n) = A034886(n) - (A027869(n) + A079680(n) + A079714(n) + A079684(n) + A079688(n) + A079691(n) + A079692(n) + A079693(n) + A079694(n)). - Reinhard Zumkeller, Jan 27 2008