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
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 30 2009
STATUS
approved