A338788 a(n) = (n!/6) * Sum_{i,j,k > 0 and i+j+k=n} A000593(i)*A000593(j)*A000593(k)/(i*j*k).

0, 0, 1, 6, 95, 585, 8974, 70252, 1178540, 10683180, 201213936, 2151034776, 46320457248, 557515105056, 12980593545984, 179077693449600, 4696518067511040, 71418673681171200, 2026061283912560640, 33687422807179092480, 1055027603388725452800, 19337685190135751577600

Offset

1,4

Links

Seiichi Manyama, Table of n, a(n) for n = 1..448

Mathematica

nmax = 50; A000593 = Table[Sum[Mod[d, 2] d, {d, Divisors[n]}], {n, 1, nmax}]; Table[n!/6 * Sum[Sum[Sum[If[i + j + k == n, A000593[[i]] * A000593[[j]] * A000593[[k]] / (i*j*k), 0], {k, 1, n}], {j, 1, n}], {i, 1, n}], {n, 1, nmax}] (* Vaclav Kotesovec, Nov 09 2020 *)

Prog

(PARI) {a(n) = my(t='t); n!*polcoef(polcoef(prod(k=1, n, (1+x^k+x*O(x^n))^t), n), 3)}

Crossrefs

Column 3 of A075525.

Cf. A000593, A059357.

Sequence in context: A180260 A058465 A290984 * A326436 A243802 A119627

Adjacent sequences: A338785 A338786 A338787 * A338789 A338790 A338791

Keyword

nonn

Author

Seiichi Manyama, Nov 09 2020

Status

approved