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A236329 a(n) = sigma(n,1) * sigma(n,2) * ... * sigma(n,n). 3
1, 15, 1120, 2929563, 38464354656, 80529415686720000, 538252697895729090560000, 1045011472134222568417452736171875, 14983270528936392555878952946810076508388237, 30023920804570215919584229032152609459437167079578240000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

sigma(n, k) is the sum of the k-th powers of the divisors of n.

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 1..35

FORMULA

log(a(n)) ~ n*(n+1)*log(n)/2. - Vaclav Kotesovec, Aug 21 2019

EXAMPLE

a(4) = sigma(4,1)*sigma(4,2)*sigma(4,3)*sigma(4,4) = 7*21*73*273 = 2929563.

MAPLE

with(NumberTheory): seq(product(sigma[k](n), k = 1..n), n = 1..10); # Vaclav Kotesovec, Aug 20 2019

MATHEMATICA

Table[Times@@DivisorSigma[Range[n], n], {n, 10}] (* Harvey P. Dale, Oct 21 2017 *)

PROG

(PARI) vector(12, n, prod(k=1, n, sigma(n, k)))

CROSSREFS

Cf. A236328.

Cf. A000203, A001157, A001158, A001159, A001160.

Sequence in context: A207980 A131313 A208346 * A129764 A027552 A212857

Adjacent sequences:  A236326 A236327 A236328 * A236330 A236331 A236332

KEYWORD

nonn

AUTHOR

Colin Barker, Jan 22 2014

STATUS

approved

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Last modified August 11 09:29 EDT 2022. Contains 356065 sequences. (Running on oeis4.)