OFFSET
0,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..295
MAPLE
seq(add(stirling1(n, k)*stirling2(n, k), k = 0..n), n = 0..20); # G. C. Greubel, Aug 07 2019
MATHEMATICA
Flatten[{1, Table[Sum[StirlingS1[n, k]*StirlingS2[n, k], {k, n}], {n, 20}] }] (* Vaclav Kotesovec, Oct 13 2018 *)
PROG
(PARI) {a(n) = sum(k=0, n, stirling(n, k, 1)*stirling(n, k, 2))};
vector(20, n, n--; a(n)) \\ G. C. Greubel, Aug 07 2019
(Magma) [(&+[StirlingFirst(n, k)*StirlingSecond(n, k): k in [0..n]]): n in [0..20]]; // G. C. Greubel, Aug 07 2019
(SageMath) [sum((-1)^(n-k)*stirling_number1(n, k)*stirling_number2(n, k) for k in (0..n)) for n in (0..20)] # G. C. Greubel, Aug 07 2019
(GAP) List([0..20], n-> Sum([0..n], k-> (-1)^(n-k)*Stirling1(n, k) *Stirling2(n, k) )); # G. C. Greubel, Aug 07 2019
CROSSREFS
KEYWORD
sign
AUTHOR
STATUS
approved