A050396 Exponential reversion of rooted trees A000081.
1, -1, 1, 1, -14, 64, -97, -1376, 15915, -68820, -467868, 11504693, -85105325, -490922106, 21504158897, -242026388646, -848338391966, 80509815160192, -1351044945506956, 1506218518200935, 472249651021870475, -11783220545826576339, 78093421491085905492
Offset: 1
Keywords
Links
- Alois P. Heinz, Table of n, a(n) for n = 1..100
- N. J. A. Sloane, Transforms
- Index entries for reversions of series
- Index entries for sequences related to rooted trees
Crossrefs
Cf. A050395.
Programs
-
Mathematica
a[n:0|1] := n; a[n_] := a[n] = Sum[m a[m] a[n-k*m], {m, n-1}, {k, (n-1)/m}]/(n-1); length = 20; Range[length]! InverseSeries[Sum[a[n] x^n/n!, {n, 0, length}] + O[x]^(length+1)][[3]] (* Vladimir Reshetnikov, Nov 06 2015 *)