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A132459 Sums of squared coefficients in the negative powers of the Catalan function: a(n) = Sum_{k=1..n+1} [x^(n-k+1)] 1/C(x^2)^k, where C(x) is the g.f. of A000108. 1
1, 1, 2, 5, 11, 18, 30, 45, 101, 171, 483, 702, 2745, 3406, 21215, 23237, 202627, 205701, 2169260, 2138431, 24770064, 24197219, 294389605, 286927242, 3600713132, 3508785697, 45050653316, 43916201874, 574363373312 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..28.

PROG

(PARI) {a(n)=local(Catalan=2/(1+sqrt(1-4*x^2 +x*O(x^n)))); sum(k=1, n+1, polcoeff(Catalan^-k, n-k+1)^2)}

CROSSREFS

Cf. A132461; A000108 (Catalan).

Sequence in context: A298375 A260037 A132455 * A308517 A101057 A045362

Adjacent sequences:  A132456 A132457 A132458 * A132460 A132461 A132462

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Aug 21 2007

STATUS

approved

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Last modified October 20 20:23 EDT 2019. Contains 328273 sequences. (Running on oeis4.)