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
Vaclav Kotesovec, Table of n, a(n) for n = 1..248
Vaclav Kotesovec, Plot of (a(n)/(n!)^2)^(1/n) for n = 1..100000
Ramanujan's Papers, Some formulas in the analytic theory of numbers, Messenger of Mathematics, XLV, 1916, 81-84, Formula (20).
FORMULA
a(n) = Product_{i=1..n} A001157(i).
Lim_{n->infinity} (a(n) / (n!)^2)^(1/n) = A345158. - Vaclav Kotesovec, Jun 10 2021
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
KEYWORD
nonn,easy
AUTHOR
Wesley Ivan Hurt, Oct 01 2014
STATUS
approved