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A095349
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Total number of edges in all trees on n nodes.
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0
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0, 1, 2, 6, 12, 30, 66, 161, 376, 954, 2350, 6061, 15612, 41067, 108374, 289800, 778064, 2105739, 5723190, 15638235, 42890100, 118098876, 326217628, 903897631, 2511285360, 6994836250, 19527701960, 54632961864, 153147864380, 430095282258, 1209924870900
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OFFSET
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1,3
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LINKS
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FORMULA
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MATHEMATICA
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nn = 25; f[x_] := Sum[a[n] x^n, {n, 0, nn}]; sol = SolveAlways[0 == Series[
f[x] - x Product[1/(1 - x^i)^a[i], {i, 1, nn}], {x, 0, nn}], x];
r[x_] := Sum[a[n] x^n, {n, 0, nn}] /. sol; Drop[Level[CoefficientList[
Series[x^2 D[1/x (r[x] - 1/2 (r[x]^2 - r[x^2])), x], {x, 0, nn}],
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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