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A356534
a(n) = sigma_3(n)^2.
3
1, 81, 784, 5329, 15876, 63504, 118336, 342225, 573049, 1285956, 1774224, 4177936, 4831204, 9585216, 12446784, 21911761, 24147396, 46416969, 47059600, 84603204, 92775424, 143712144, 148060224, 268304400, 248094001, 391327524, 417793600, 630612544, 594872100
OFFSET
1,2
LINKS
Ramanujan's Papers, Some formulas in the analytic theory of numbers, Messenger of Mathematics, XLV, 1916, 81-84, Formula (15), a=b=3.
FORMULA
Dirichlet g.f.: zeta(s) * zeta(s-3)^2 * zeta(s-6) / zeta(2*s-6).
Multiplicative with a(p^e) = ((p^(3*e+3)-1)/(p^3-1))^2. - Amiram Eldar, Aug 11 2022
MATHEMATICA
Table[DivisorSigma[3, n]^2, {n, 1, 40}]
PROG
(PARI) a(n) = sigma(n, 3)^2; \\ Michel Marcus, Aug 11 2022
CROSSREFS
Cf. A001158, A127473, A035116, A072861, A356536 (partial sums).
Sequence in context: A271829 A066431 A206086 * A224002 A253461 A247842
KEYWORD
nonn,mult
AUTHOR
Vaclav Kotesovec, Aug 11 2022
STATUS
approved