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Search: id:A136551
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| A136551 |
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a(n) = C(2^n + 2*n + 1, n)*(2^n + 1)/(2^n + 2*n + 1); a(n) = coefficient of x^n in Catalan(x)^(2^n+1). |
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+0
3
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| 1, 3, 20, 273, 8602, 738738, 200144100, 188542438797, 649522995031926, 8346577591515964350, 402021093245772461553820, 72549434962879252821217976994, 48999971145855741423248927935058060
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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G.f.: A(x) = Sum_{n>=0} Catalan(2^n*x) * log( Catalan(2^n*x) )^n / n! where Catalan(x) = 2/(1+sqrt(1-4*x)).
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EXAMPLE
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G.f.: A(x) = 1 + 3*x + 20*x^2 + 273*x^3 + 8602*x^4 + 738738*x^5 +...
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PROGRAM
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(PARI) {a(n)=binomial(2^n + 2*n + 1, n)*(2^n + 1)/(2^n + 2*n + 1)} (PARI) {a(n)=polcoeff((2/(1+sqrt(1-4*x +x*O(x^n))))^(2^n+1), n)} (PARI) {a(n)=polcoeff(sum(k=0, n, 2/(1+sqrt(1-4*2^k*x +x*O(x^n)))*log( 2/(1+sqrt(1-4*2^k*x +x*O(x^n))))^k/k!), n)}
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CROSSREFS
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Cf. A136550, A136552.
Sequence in context: A119758 A108527 A166232 this_sequence A086229 A130531 A163138
Adjacent sequences: A136548 A136549 A136550 this_sequence A136552 A136553 A136554
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jan 05 2008
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