A144659 a(n) = A001516(n)/2.

0, 0, 3, 60, 990, 16485, 292215, 5602338, 116549370, 2627202105, 63960690420, 1675359272730, 47031228602358, 1409683851264780, 44956320071089245, 1520493296271210030, 54376042036599780570, 2050556012681642525763, 81336729496634645414265, 3385729099078381669910310

Offset: 0

Author

N. J. A. Sloane, Jan 30 2009

Keywords

• nonn

Formula

Also a(n) = 3*A144507(n).

Also a(n) = Sum_{k} binomial(k-n,2) T(n,k) where T(n,k) is the triangle in A144331.