A132785 Main diagonal of triangle A132784.

1, 1, 1, 1, 2, 7, 40, 342, 4118, 66581, 1393998, 36722251, 1189340060, 46466456210, 2155486553918, 117137645018204, 7372271485024724, 532031521606758006, 43644205623323138712, 4038679603699275061593, 418716209086799704826908

Offset

0,5

Comments

Also equals (with offset) the row sums and rightmost border of triangle A132784.

Links

Table of n, a(n) for n=0..20.

Prog

(PARI) {a(n)=local(A=[1]); if(n==0, 1, for(i=1, n, B=Vec(Pol(A)/(1-x +x*O(x^(i*(i-1)/2)))); A=concat(vector(i), B)); A[n+1])}

Crossrefs

Cf. A132784 (triangle), A132786 (column sums).

Sequence in context: A031973 A274279 A319945 * A224677 A064626 A137731

Adjacent sequences: A132782 A132783 A132784 * A132786 A132787 A132788

Keyword

nonn

Author

Paul D. Hanna, Aug 29 2007

Status

approved