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A247951 a(n) = Product_{i=1..n} sigma_2(i). 1
1, 5, 50, 1050, 27300, 1365000, 68250000, 5801250000, 527913750000, 68628787500000, 8372712075000000, 1758269535750000000, 298905821077500000000, 74726455269375000000000, 19428878370037500000000000, 6625247524182787500000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

a(n) is the product of the sum of the squared divisors of i, for i from 1 to n.

LINKS

Table of n, a(n) for n=1..16.

FORMULA

a(n) = Product_{i=1..n} A001157(i).

MAPLE

with(numtheory): A247951:=n->mul(sigma[2](i), i=1..n): seq(A247951(n), n=1..20);

MATHEMATICA

Table[Product[DivisorSigma[2, i], {i, n}], {n, 20}]

PROG

(PARI) lista(nn) = vector(nn, n, prod(i=1, n, sigma(i, 2))) \\ Michel Marcus, Oct 01 2014

CROSSREFS

Cf. A000203 (sigma), A001157 (sigma_2), A066780 (product{i=1..n} sigma(i)).

Sequence in context: A320502 A116906 A051893 * A082100 A299353 A180976

Adjacent sequences:  A247948 A247949 A247950 * A247952 A247953 A247954

KEYWORD

nonn,easy

AUTHOR

Wesley Ivan Hurt, Oct 01 2014

STATUS

approved

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Last modified April 18 12:34 EDT 2019. Contains 322209 sequences. (Running on oeis4.)