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A093113
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Coefficients of the solution to a functional equation.
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0
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1, 2, 6, 16, 62, 192, 652, 2048, 9270, 31744, 116948, 393216, 1533868, 5341184, 19445016, 67108864, 332958758, 1215037440, 4711687300, 16642998272, 67697833092, 245257732096, 923984441000, 3298534883328, 13952454631996
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| G.f. A(x) satisfies A(4x^2)=A(x)+A(-x)=-4A(x)A(-x). Also A(4x^2)=4A(x)^2/(1+4A(x)).
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PROG
| (PARI) a(n)=local(A, m); if(n<1, 0, A=x+O(x^2); m=1; while(m<=n, m*=2; A=subst(A, x, x^2); A=A/2+sqrt(A^2/4+A)); polcoeff(A, n)*4^(n-1))
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CROSSREFS
| Sequence in context: A027742 A033301 A197102 * A150030 A150031 A121753
Adjacent sequences: A093110 A093111 A093112 * A093114 A093115 A093116
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KEYWORD
| nonn
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AUTHOR
| Michael Somos, Mar 20 2004
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