A137648 a(n) = Sum_{k=0..n} C(k^2, k) * C(k^2, n-k).

1, 1, 7, 108, 2612, 85298, 3501504, 172989880, 9987924928, 659768790882, 49065577842538, 4056413252138692, 369030922581806616, 36634832808175143734, 3940779041158898056286, 456592594401713997379344

Offset

0,3

Links

Table of n, a(n) for n=0..15.

Mathematica

Table[Sum[Binomial[k^2, k]Binomial[k^2, n-k], {k, 0, n}], {n, 0, 20}] (* Harvey P. Dale, Dec 05 2012 *)

Prog

(PARI) a(n)=sum(k=0, n, binomial(k^2, k)*binomial(k^2, n-k))

Crossrefs

Sequence in context: A218819 A033516 A130629 * A106977 A142480 A202515

Adjacent sequences: A137645 A137646 A137647 * A137649 A137650 A137651

Keyword

nonn

Author

Paul D. Hanna, Jan 31 2008

Status

approved