A144658 a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} (i+j+k)!/(i!*j!*k!).

0, 6, 222, 5052, 109512, 2432448, 55611294, 1301187912, 30992726652, 748573575780, 18283412752602, 450657126652626, 11192820097106112, 279787295335659972, 7032532241701837758, 177611430241032329568

Offset

0,2

Links

Seiichi Manyama, Table of n, a(n) for n = 0..100

Mathematica

Table[Sum[Sum[Sum[(i+j+k)!/i!/j!/k!, {i, 1, n}], {j, 1, n}], {k, 1, n}], {n, 1, 30}]

Prog

(PARI) {a(n) = sum(i=1, n, sum(j=1, n, sum(k=1, n, (i+j+k)!/(i!*j!*k!))))} \\ Seiichi Manyama, May 19 2019
(PARI) {a(n) = sum(i=3, 3*n, i!*polcoef(sum(j=1, n, x^j/j!)^3, i))} \\ Seiichi Manyama, May 19 2019

Crossrefs

Cf. A144511.

Sequence in context: A292692 A015477 A331477 * A203637 A144045 A355669

Adjacent sequences: A144655 A144656 A144657 * A144659 A144660 A144661

Keyword

nonn

Author

N. J. A. Sloane, Jan 30 2009

Status

approved