A307369 a(n) = -Sum_{0<=i<j<k<=n} (-1)^(i+j+k) * (i+j+k)!/(i!*j!*k!).

0, 0, 3, -51, 1059, -23090, 522721, -12147685, 287854454, -6924261148, 168559758222, -4143307764311, 102667574424349, -2561308686267644, 64269232404321663, -1620744761933019015, 41050609554433557263, -1043736712034774976330, 26628094150076388266301

Offset

0,3

Links

Table of n, a(n) for n=0..18.

Mathematica

Table[-Sum[Sum[Sum[(-1)^(i+j+k) * (i + j + k)!/(i!*j!*k!), {i, 0, j-1}], {j, 0, k-1}], {k, 0, n}], {n, 0, 20}] (* Amiram Eldar, May 20 2021 *)

Prog

(PARI) {a(n) = -sum(i=0, n, sum(j=i+1, n, sum(k=j+1, n, (-1)^(i+j+k)*(i+j+k)!/(i!*j!*k!))))}

Crossrefs

Cf. A306409, A306432, A307358.

Sequence in context: A182512 A075869 A361051 * A126685 A355797 A246693

Adjacent sequences: A307366 A307367 A307368 * A307370 A307371 A307372

Keyword

sign

Author

Seiichi Manyama, Apr 05 2019

Status

approved