A126157 Main diagonal and central terms of symmetric triangle A126155.

1, 5, 55, 1415, 69025, 5403005, 616437655, 96365988815, 19756766836225, 5140259013390005, 1654190282113104055, 645005323804145184215, 299613583126435893179425, 163464903833408195554809005

Offset: 0

Author

Paul D. Hanna, Dec 20 2006

Keywords

• nonn

Crossrefs

Cf. A126155; A126156 (column 0), A126158 (diagonal).

Formula

a(n)=Sum_{k, 0<=k<=n}A130847(n,k)*4^k. - Philippe Deléham, Jul 22 2007