OFFSET
0,3
COMMENTS
A leaf is a vertex of degree 1.
FORMULA
MAPLE
b:= proc(n) option remember; `if`(n=0, 1, 2^(n*(n-1)/2)-
add(k*binomial(n, k)* 2^((n-k)*(n-k-1)/2)*b(k), k=1..n-1)/n)
end:
a:= n-> n*(n-1)*b(n-1):
seq(a(n), n=0..20); # Alois P. Heinz, Jul 31 2016
MATHEMATICA
nn = 15; Clear[f]; f[z_] := Sum[2^Binomial[n, 2] z^n/n!, {n, 0, nn + 1}]; Range[0, nn]! CoefficientList[Series[ z z D[Log[f[z]], z] , {z, 0, nn}], z]
CROSSREFS
KEYWORD
nonn
AUTHOR
Geoffrey Critzer, Jul 28 2016
STATUS
approved