A082760 Trinomial transform of central binomial coefficients (A000984).

1, 9, 133, 2283, 41589, 782149, 15007831, 291987327, 5738781717, 113670432141, 2265365597553, 45371770152927, 912463490703879, 18413786266130979, 372689501160357787, 7562267679664012693, 153785739808245476757

Offset: 0

Author

Emanuele Munarini, May 21 2003

Keywords

• easy
• nonn

Formula

a(n) = Sum[ Binomial[2k, k] Trinomial[n, k], {k, 0, 2n} ] where Trinomial[n, k] = trinomial coefficients (A027907)

a(n)=sum{k=0..n, sum{j=0..n, C(n, j)C(j, k)C(2(j+k), j+k)}}; - Paul Barry, Feb 15 2005