OFFSET
0,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..330
A. Fekete and G. Martin, Problem 10791: Squared Series Yielding Integers, Amer. Math. Monthly, 108 (No. 2, 2001), 177-178.
MAPLE
with(combinat): seq(-bell(n)*BellB(n, -1), n = 0..25); # G. C. Greubel, Oct 08 2019
MATHEMATICA
Table[-BellB[n]*BellB[n, -1], {n, 0, 25}] (* G. C. Greubel, Oct 08 2019 *)
PROG
(PARI) a(n) = (-1)*sum(k=0, n, stirling(n, k, 2))*sum(k=0, n, (-1)^k*stirling(n, k, 2));
vector(25, n, a(n-1)) \\ G. C. Greubel, Oct 08 2019
(Magma) a:= func< n | (-1)*(&+[StirlingSecond(n, k): k in [0..n]])*(&+[ (-1)^k*StirlingSecond(n, k): k in [0..n]]) >;
[a(n): n in [0..25]]; // G. C. Greubel, Oct 08 2019
(Sage) [ -sum(stirling_number2(n, k) for k in (0..n))*sum((-1)^k* stirling_number2(n, k) for k in (0..n)) for n in (0..25)] # G. C. Greubel, Oct 08 2019
(GAP) List([0..25], n-> (-1)*Sum([0..n], k-> Stirling2(n, k)) *Sum([0..n], k-> (-1)^k*Stirling2(n, k)) ); # G. C. Greubel, Oct 08 2019
CROSSREFS
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Sep 05 2006
STATUS
approved