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Search: id:A104969
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| 1, 2, 6, 12, 18, 36, 92, 184, 298, 596, 1444, 2888, 4852, 9704, 22840, 45680, 78490, 156980, 362580, 725160, 1265564, 2531128, 5767688, 11535376, 20366596, 40733192, 91866984, 183733968, 327351336, 654702672, 1464522864, 2929045728
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OFFSET
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0,2
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FORMULA
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a(2*n+1) = 2*a(2*n). G.f.: A(x) = (1+2*x)*G(x^2) where G(x) is the g.f. of A104970 such that G(x) satisfies: 2*(1+12*x)*G(x) - (1-16*x^2)*deriv(G(x), x) + 4 = 0.
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PROGRAM
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(PARI) {a(n)=local(X=x+x*O(x^n)); sum(k=0, n, polcoeff(polcoeff((1-2*X)/(1-X-X*y*(1-2*X)), n, x), k, y)^2)}
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CROSSREFS
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Cf. A104967, A104970.
Sequence in context: A117311 A125024 A053660 this_sequence A065005 A139084 A086958
Adjacent sequences: A104966 A104967 A104968 this_sequence A104970 A104971 A104972
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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), Mar 30 2005
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