A079684 Number of 3's in n!.

0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 2, 0, 1, 2, 1, 1, 0, 0, 1, 5, 3, 2, 1, 3, 3, 2, 1, 7, 2, 3, 7, 4, 5, 1, 5, 3, 5, 3, 9, 3, 5, 1, 5, 7, 6, 6, 6, 4, 9, 8, 5, 3, 4, 5, 8, 8, 4, 8, 5, 9, 7, 7, 6, 9, 10, 5, 7, 8, 6, 10, 7, 11, 7, 9, 10, 8, 8, 15, 10, 13, 8, 10, 13, 8, 12, 10, 6, 18, 12, 12, 15, 9, 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. A079714.

Cf. A000142, A137579, A137580.

Programs

Mathematica

DigitCount[Range[0,100]!,10,3] (* Harvey P. Dale, Jul 04 2014 *)

Formula

a(n) = A034886(n) - (A027869(n) + A079680(n) + A079714(n) + A079688(n) + A079690(n) + A079691(n) + A079692(n) + A079693(n) + A079694(n)). - Reinhard Zumkeller, Jan 27 2008

Extensions

Corrected by Jason Earls, Jul 06 2003