A259696 a(n) = Sum_{k=1..n-1} k^8*sigma(k)*sigma(n-k).

0, 1, 771, 28552, 540563, 3830364, 29209978, 119337536, 490114881, 1659932478, 4961414965, 12516905184, 33139873949, 77515802840, 156374512326, 344012784128, 669604434612, 1292506329141, 2292202227639, 4210108803824, 6929184038448, 12639642518772, 19287324979742, 32384260599552

Offset: 1

Author

N. J. A. Sloane, Jul 03 2015

Keywords

• nonn

Comments

This was formerly A001481.

Links

• Colin Barker, Table of n, a(n) for n = 1..1000
• J. Touchard, On prime numbers and perfect numbers, Scripta Math., 129 (1953), 35-39. [Annotated scanned copy]

Crossrefs

Cf. A000385, A000441, A000477, A000499, A259692, A259693, A259694, A259695.

Programs

Maple

S:=(n,e)->add(k^e*sigma(k)*sigma(n-k),k=1..n-1); f:=e->[seq(S(n,e),n=1..30)]; f(8);

PARI

a(n) = sum(k=1, n-1, k^8*sigma(k)*sigma(n-k)) \\ Colin Barker, Jul 16 2015