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A131927
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Series reversion of x * (1 - 9*x) / (1 - x).
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2
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0, 1, 8, 136, 2888, 68680, 1749896, 46707976, 1289214152, 36496595656, 1053849164552, 30918300671368, 919029058099784, 27617782977715528, 837674888992142984, 25610757376777402888, 788450850824647610312
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OFFSET
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0,3
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COMMENTS
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The Hankel transform of this sequence is 72^C(n+1,2) .
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LINKS
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Table of n, a(n) for n=0..16.
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FORMULA
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a(n) = Sum_{k, 0<=k<=n} A086810(n,k)*8^k .
G.f.: (1+x-sqrt(1-34*x+x^2))/18. - Emeric Deutsch, Nov 19 2007
a(n) = - a(n-1) + 9 * Sum_{k=1..n-1} a(k) * a(n-k) if n>1. - Michael Somos, Jul 23 2011
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EXAMPLE
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x + 8*x^2 + 136*x^3 + 2888*x^4 + 68680*x^5 + 1749896*x^6 + 46707976*x^7 + ...
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MAPLE
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G:=(1+x-sqrt(1-34*x+x^2))*1/18: Gser:=series(G, x=0, 21): seq(coeff(Gser, x, n), n =0..17); - Emeric Deutsch, Nov 19 2007
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PROG
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(PARI) {a(n) = local(A); if( n<1, 0, A = vector(n); A[1] = 1; for( k=2, n, A[k] = - A[k-1] + 9 * sum( j=1, k-1, A[j] * A[k-j])); A[n])} /* Michael Somos, Jul 23 2011 */
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CROSSREFS
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Sequence in context: A069988 A072072 A195614 * A132869 A036915 A049211
Adjacent sequences: A131924 A131925 A131926 * A131928 A131929 A131930
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KEYWORD
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nonn
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AUTHOR
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Philippe DELEHAM, Oct 29 2007
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EXTENSIONS
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More terms from Emeric Deutsch, Nov 19 2007
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STATUS
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approved
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