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A259694 a(n) = Sum(k^6*sigma(k)*sigma(n-k),k=1..n-1). 1
0, 1, 195, 3496, 38195, 192780, 977386, 3216320, 9860049, 27321870, 65803045, 144005856, 308944925, 635774072, 1112550390, 2153146880, 3618341556, 6391671525, 9949570455, 16725562160, 24691972080, 40979569092, 56807498030, 89450231040, 120404165825 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

This was formerly A001479.

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(6);

PROG

(PARI) a(n) = sum(k=1, n-1, k^6*sigma(k)*sigma(n-k)) \\ Colin Barker, Jul 16 2015

CROSSREFS

Sequence in context: A172354 A295130 A257765 * A066232 A284960 A226105

Adjacent sequences:  A259691 A259692 A259693 * A259695 A259696 A259697

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Jul 03 2015

STATUS

approved

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Last modified December 6 19:15 EST 2021. Contains 349567 sequences. (Running on oeis4.)