A079691 Number of 6's in n!.

0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 2, 0, 2, 1, 1, 2, 0, 2, 3, 2, 0, 4, 3, 2, 3, 3, 2, 5, 3, 4, 7, 2, 3, 5, 2, 3, 6, 5, 6, 5, 8, 4, 7, 6, 6, 9, 5, 8, 7, 3, 9, 6, 7, 4, 6, 8, 6, 6, 11, 6, 8, 8, 11, 6, 4, 11, 11, 10, 6, 5, 9, 8, 9, 8, 11, 10, 8, 11, 12, 13, 9, 11, 7, 12, 15, 15, 17, 8, 11, 16, 11

Offset: 0

Author

Cino Hilliard, Jan 31 2003

Keywords

• easy
• nonn
• base

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

Table[DigitCount[n!,10,6],{n,0,100}] (* Harvey P. Dale, Aug 08 2023 *)

Formula

a(n) = A034886(n) - (A027869(n) + A079680(n) + A079714(n) + A079684(n) + A079688(n) + A079690(n) + A079692(n) + A079693(n) + A079694(n)). - Reinhard Zumkeller, Jan 27 2008