A319359 - OEIS

A319359

Expansion of Product_{i>=1, j>=1, k>=1} (1 - x^(i*j*k)).

1, -1, -3, 0, 0, 9, 5, 4, -1, -27, -2, -33, -17, 8, 43, 92, 36, 100, -8, -11, -136, -120, -296, -363, -13, -203, 286, 306, 1010, 667, 724, 790, 151, -258, -1207, -964, -3325, -2059, -2924, -1992, -2116, 1277, 3625, 4437, 7724, 7734, 11524, 5801, 9685, -855, -2799, -13409, -16423

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OFFSET

0,3

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..10000

FORMULA

G.f.: Product_{k>=1} (1 - x^k)^A007425(k).

G.f.: exp(-Sum_{k>=1} A174466(k)*x^k/k).

MAPLE

a:=series(mul(mul(mul(1-x^(i*j*k), k=1..55), j=1..55), i=1..55), x=0, 53): seq(coeff(a, x, n), n=0..52); # Paolo P. Lava, Apr 02 2019

MATHEMATICA

nmax = 52; CoefficientList[Series[Product[(1 - x^(i j k)), {i, 1, nmax}, {j, 1, nmax/i}, {k, 1, nmax/i/j}], {x, 0, nmax}], x]

nmax = 52; CoefficientList[Series[Product[(1 - x^k)^Sum[DivisorSigma[0, d], {d, Divisors[k]}], {k, 1, nmax}], {x, 0, nmax}], x]

a[n_] := a[n] = If[n == 0, 1, -Sum[Sum[d DivisorSigma[1, k/d] DivisorSigma[0, d], {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 52}]

CROSSREFS

Cf. A000005, A000203, A007425, A174465, A174466, A280473, A288098.

Sequence in context: A011073 A200287 A216469 * A104751 A265828 A177016

Adjacent sequences: A319356 A319357 A319358 * A319360 A319361 A319362

KEYWORD

sign

AUTHOR

Ilya Gutkovskiy, Sep 17 2018

STATUS

approved