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Search: id:A141118
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| A141118 |
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G.f. A(x) satisfies: A(A(A(x))) = x + 9*x^2. |
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+0
3
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| 1, 3, -18, 189, -2430, 34020, -486972, 6786261, -86946372, 919825956, -5269375296, -80180038944, 3575424508272, -77211406919844, 1164244485947400, -12342809241883386, 102419678663170128, -2040575112980362980
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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G.f.: A(x) = x + 3*x^2 - 18*x^3 + 189*x^4 - 2430*x^5 + 34020*x^6 -+...
A(A(x)) = x + 6*x^2 - 18*x^3 + 135*x^4 - 1296*x^5 + 13122*x^6 -+...
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PROGRAM
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(PARI) {a(n, m=3)=local(F=x+m*x^2+x*O(x^n), G); if(n<1, 0, for(k=3, n, G=F+x*O(x^k); for(i=1, m-1, G=subst(F, x, G)); F=F+((-polcoeff(G, k))/m)*x^k); return(polcoeff(F, n, x)))}
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CROSSREFS
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Cf. A027436, A141119, A141120, A141121.
Sequence in context: A006472 A132853 A084879 this_sequence A033030 A002824 A160707
Adjacent sequences: A141115 A141116 A141117 this_sequence A141119 A141120 A141121
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KEYWORD
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sign
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jun 05 2008
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