OFFSET
2,1
REFERENCES
G. P. Egorychev et al., Enumeration of ideals of some nilpotent matrix rings, J. Algebra and Applications, 12 (2013), #1250140.
MAPLE
f:=(n, s)->(2*s*n-s-3*n+1)*binomial(2*n-2, n-1)-(4/n)*binomial(2*n, n-2)+2^(2*n-1);
[seq(f(n, 4), n=2..40)];
PROG
(Maxima) A221704(n, s):=(2*s*n-s-3*n+1)*binomial(2*n-2, n-1)-(4/n)*binomial(2*n, n-2)+2^(2*n-1)$
makelist(A221704(n, 4), n, 2, 40); /* Martin Ettl, Jan 24 2013 */
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 22 2013
STATUS
approved