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Search: id:A125280
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| 1, 2, 5, 15, 53, 217, 1011, 5260, 30041, 185677, 1228209, 8620874, 63792445, 495163451, 4015888557, 33923543492, 297706713081, 2708377382444, 25495655264883, 247952347547483, 2487743315817023, 25717746952124842
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OFFSET
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0,2
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FORMULA
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G.f.: A(x) = (1/x)*G(x)/(1 - G(x)) where G(x) = x + x*G(G(x)) is g.f. of A030266.
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EXAMPLE
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A(x) = 1 + 2*x + 5*x^2 + 15*x^3 + 53*x^4 + 217*x^5 + 1011*x^6 +...
where 1 - 1/(1 + x*A(x)) = G(x) is the g.f. of A030266:
G(x) = x + x^2 + 2*x^3 + 6*x^4 + 23*x^5 + 104*x^6 + 531*x^7 + 2982*x^8+..
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PROGRAM
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(PARI) {a(n)=local(G=x+x^2); for(i=0, n, G=x+x*subst(G, x, G+x^2*O(x^n))); polcoeff((-1+1/(1-G))/x, n, x)}
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CROSSREFS
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Cf. A125280, A030266.
Sequence in context: A006790 A007548 A120567 this_sequence A022493 A006966 A056841
Adjacent sequences: A125277 A125278 A125279 this_sequence A125281 A125282 A125283
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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), Nov 26 2006
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