OFFSET
0,6
LINKS
N. J. A. Sloane, Illustration of first 5 terms
Peter Steinbach, Field Guide to Simple Graphs, Volume 4, Part 11 (For Volumes 1, 2, 3, 4 of this book see A000088, A008406, A000055, A000664, respectively.)
FORMULA
E.g.f.: 1/(1-y*(1-1/A(x))) where A(x) is the e.g.f. for A006125.
EXAMPLE
Triangle T(n,k) begins:
1;
0, 1;
0, 0, 2;
0, 2, 0, 6;
0, 24, 16, 0, 24;
0, 544, 240, 120, 0, 120;
0, 22320, 6608, 2160, 960, 0, 720;
...
MATHEMATICA
nn = 10; G[x_] := Sum[2^Binomial[n, 2] x^n/n!, {n, 0, nn}]; Table[
Take[(Range[0, nn]! CoefficientList[Series[1/(1 - y (1 - 1/ G[x])), {x, 0, nn}], {x, y}])[[i]], i], {i, 1, nn}]
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Geoffrey Critzer, Jul 08 2022
STATUS
approved