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A136631 Antidiagonal sums of triangle A136630, omitting antidiagonals of all zeros. 1
1, 1, 2, 6, 28, 177, 1449, 14869, 185230, 2738962, 47287352, 939759621, 21241309681, 540698975061, 15370957337418, 484433735633218, 16817886069720724, 639545680226171989, 26507567678760284105 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 14 19:59 EST 2019. Contains 329128 sequences. (Running on oeis4.)