A136631 Antidiagonal sums of triangle A136630, omitting antidiagonals of all zeros.

1, 1, 2, 6, 28, 177, 1449, 14869, 185230, 2738962, 47287352, 939759621, 21241309681, 540698975061, 15370957337418, 484433735633218, 16817886069720724, 639545680226171989, 26507567678760284105

Offset

0,3

Links

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

Formula

a(n) = Sum_{k=0..n} [x^(2n-2k)] Product_{j=0..[k/2]} 1/(1 - (2j + k-2[k/2])^2*x^2).

Prog

(PARI) {a(n)=sum(k=0, n, polcoeff(1/prod(j=0, k\2, 1-(2*j+(k%2))^2*x^2 +x*O(x^(2*n-2*k))), 2*n-2*k))}

Crossrefs

Cf. A136630, A003724 (row sums of A136630).

Sequence in context: A088501 A140092 A052809 * A002435 A276911 A104018

Adjacent sequences: A136628 A136629 A136630 * A136632 A136633 A136634

Keyword

nonn

Author

Paul D. Hanna, Jan 14 2008

Status

approved