A136469 Column 2 of triangle A136467 (scaled): a(n) = A136467(n+2,2)/4^n.

1, 4, 36, 972, 82692, 22668224, 20480767016, 62399482333360, 654732295896172624, 24092174555680443592896, 3156168229958886081384337440, 1490220874303979634022445823087616

Offset: 0

Author

Paul D. Hanna, Dec 31 2007

Keywords

• nonn

Crossrefs

Cf. A136467; A136468.

Programs

PARI

{a(n)=local(M=matrix(n+3,n+3,r,c,binomial(r*2^(c-2),c-1)),P); P=matrix(n+3,n+3,r,c,binomial((r+1)*2^(c-2),c-1));(P~*M~^-1)[n+3,3]/4^n}