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%I #20 Jun 21 2018 00:15:23
%S 1,-1,0,1,-1,1,-4,11,-18,18,0,-60,189,-360,453,-373,294,-652,1443,
%T -841,-6127,27681,-75150,172371,-389662,867415,-1630604,1826409,
%U 1738343,-15855044,49812000,-109702703,186277940,-229343877,86783346,618570769,-2635628596
%N Reversion of rooted trees A000081.
%H Alois P. Heinz, <a href="/A050395/b050395.txt">Table of n, a(n) for n = 1..100</a>
%H M. Drmota, B. Gittenberger, <a href="https://doi.org/10.1016/j.ejc.2010.05.011">The shape of unlabeled rooted random trees</a>, Eur. J. Comb. 31 (2010) no 8, 2028-2063, Remark.
%H N. J. A. Sloane, <a href="/transforms.txt">Transforms</a>
%H <a href="/index/Res#revert">Index entries for reversions of series</a>
%H <a href="/index/Ro#rooted">Index entries for sequences related to rooted trees</a>
%t Module[{t}, t[1] = 1; t[k_] := t[k] = Sum[DivisorSum[k - m, t[#] # &] t[m]/(k-1), {m, k-1}]; InverseSeries[Sum[t[n] x^n, {n, 1, 40}] + O[x]^41][[3]]] (* _Vladimir Reshetnikov_, Nov 03 2015 *)
%Y Cf. A050396, A000081.
%K sign
%O 1,7
%A _Christian G. Bower_, Nov 15 1999
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