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A259696 a(n) = Sum(k^8*sigma(k)*sigma(n-k),k=1..n-1). 1
0, 1, 771, 28552, 540563, 3830364, 29209978, 119337536, 490114881, 1659932478, 4961414965, 12516905184, 33139873949, 77515802840, 156374512326, 344012784128, 669604434612, 1292506329141, 2292202227639, 4210108803824, 6929184038448, 12639642518772, 19287324979742, 32384260599552 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

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]

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);

PROG

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

CROSSREFS

Cf. A000441.

Sequence in context: A252550 A252558 A252559 * A114543 A233647 A285755

Adjacent sequences:  A259693 A259694 A259695 * A259697 A259698 A259699

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jul 03 2015

STATUS

approved

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Last modified October 21 16:25 EDT 2019. Contains 328302 sequences. (Running on oeis4.)