A195209 Sum of even divisors of !n.

0, 0, 0, 2, 0, 72, 0, 2704, 0, 268128, 0, 17621496, 0, 4974281208, 0, 549790303712, 0, 245357774621280, 0, 67684833350266496, 0, 36434223374991414336, 0, 10781900341537812480000, 0, 14585451990785851336761600, 0, 4706112122106541811177554944, 0, 5607912482098966721098538956800, 0

Offset

0,4

Links

Amiram Eldar, Table of n, a(n) for n = 0..82

Formula

From Amiram Eldar, Aug 02 2024: (Start)

a(n) = A146076(A000166(n)), for n != 1.

a(2*n) = 0. (End)

Example

a(7) = 2704 because the divisors of  !7 = 1854 are  {1, 2, 3, 6, 9, 18, 103, 206, 309, 618, 927, 1854}, and the sum of the 6  even divisors  2, 6, 18, 206, 618 and 1854 is 2704.

Mathematica

Table[Total[Select[Divisors[Subfactorial[n]], EvenQ[ # ]&]], {n, 0, 25}]

Crossrefs

Cf. A000166, A146076, A195207, A195208, A195210.

Sequence in context: A264437 A394970 A306061 * A098276 A335692 A215880

Adjacent sequences: A195206 A195207 A195208 * A195210 A195211 A195212

Keyword

nonn

Author

Michel Lagneau, Sep 13 2011

Extensions

a(26)-a(30) from Amiram Eldar, Aug 02 2024

Status

approved