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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
OFFSET
0,3
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 A375714 A101057
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Aug 21 2007
STATUS
approved