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0, 0, 0, 0, 1, 2, 5, 10, 22, 46, 105, 234, 550, 1300, 3158, 7740, 19319, 48628, 123866, 317954, 823064, 2144504, 5623755, 14828073, 39299896, 104636889, 279793449, 751065459, 2023443031, 5469566584, 14830871801, 40330829029, 109972410220, 300628862479
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,6
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COMMENTS
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Number of free trees with n nodes, each node with degree <= n-2. - Robert A. Russell, Jan 25 2023
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LINKS
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FORMULA
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MATHEMATICA
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b[n_, i_, t_, k_] := b[n, i, t, k] = If[i<1, 0, Sum[Binomial[b[i-1, i-1, k, k]
+ j-1, j]* b[n-i*j, i-1, t-j, k], {j, 0, Min[t, n/i]}]];
b[0, i_, t_, k_] = 1;
Join[{0, 0, 0, 0, 1}, Table[m = n - 3;
gf[x_] := 1 + Sum[b[j - 1, j - 1, m, m] x^j, {j, 1, n}];
ci[x_] := SymmetricGroupIndex[m + 1, x] /. x[i_] -> gf[x^i];
SeriesCoefficient[Series[gf[x] - (gf[x]^2 - gf[x^2])/2 + x ci[x],
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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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