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A135867
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G.f. A(x) = 1 + x*A(2x)^2.
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8
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1, 1, 4, 36, 640, 21888, 1451008, 188941312, 48768745472, 25069815595008, 25722272102744064, 52730972085034156032, 216091838647321476726784, 1770657164881170759078117376, 29013990909330956353981535748096
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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COMMENTS
| Self-convolution equals A135868.
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FORMULA
| a(n) = 2^(n-1)*Sum_{k=0..n-1} a(k)*a(n-k-1) for n>0 with a(0)=1. [From Paul D. Hanna (pauldhanna(AT)juno.com), Feb 09 2010]
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PROG
| (PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A, x, 2*x)^2); polcoeff(A, n)}
(PARI) a(n)=if(n==0, 1, 2^(n-1)*sum(k=0, n-1, a(k)*a(n-k-1))) [From Paul D. Hanna (pauldhanna(AT)juno.com), Feb 09 2010]
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CROSSREFS
| Cf. A135868.
Sequence in context: A086879 A002761 A002084 * A029989 A163887 A156630
Adjacent sequences: A135864 A135865 A135866 * A135868 A135869 A135870
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KEYWORD
| nonn
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AUTHOR
| Paul D. Hanna (pauldhanna(AT)juno.com), Dec 02 2007
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