A227469 a(n) = binomial((n+1)^2, n) * (2*n+1) / (n+1)^2 for n>=0.

1, 3, 20, 245, 4554, 115192, 3709992, 145597545, 6750522350, 361424043596, 21958844607336, 1493260499980119, 112400273159533800, 9279595605913516080, 833858283261973732944, 81027308003810095983825, 8466793463341565312119830, 946776552967215128481968260, 112816032067073649248569919400

Offset

0,2

Links

Table of n, a(n) for n=0..18.

Formula

a(n) = (2*n+1)*A143669(n).

Example

 G.f.: A(x) = 1 + 3*x + 20*x^2 + 245*x^3 + 4554*x^4 + 115192*x^5 +...

Prog

 (PARI) {a(n)=binomial((n+1)^2, n)*(2*n+1)/(n+1)^2}
for(n=0, 20, print1(a(n), ", "))

Crossrefs

Cf. A143669.

Sequence in context: A237431 A237652 A256018 * A349928 A262208 A324955

Adjacent sequences: A227466 A227467 A227468 * A227470 A227471 A227472

Keyword

nonn

Author

Paul D. Hanna, Aug 23 2013

Status

approved