OFFSET
0,5
COMMENTS
REFERENCES
F. Harary and E. Palmer, Graphical Enumeration, Academic Press,1973, page 30, exercise 1.10.
FORMULA
E.g.f.: A(x + y*x) where A(x) is the e.g.f. for A000272.
EXAMPLE
1,
1, 1,
1, 2, 1,
3, 9, 9, 3,
16, 64, 96, 64, 16,
125, 625, 1250, 1250, 625, 125,
1296, 7776, 19440, 25920, 19440, 7776, 1296
MATHEMATICA
nn = 6; f[x_] := Sum[n^(n - 2) x^n/n!, {n, 1, nn}];
Map[Select[#, # > 0 &] &,
Range[0, nn]! CoefficientList[
Series[f[x + y x] + 1, {x, 0, nn}], {x, y}]] // Grid
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Geoffrey Critzer, Nov 02 2014
STATUS
approved