OFFSET
0,2
COMMENTS
More generally, for m integer, exp( Sum_{n>=1} (m^n + y)^n * x^n/n ) is a power series in x and y with integer coefficients.
FORMULA
G.f.: A(x,y) = Sum_{n>=0} Sum_{k>=0} T(n,k)*x^n*y^k.
EXAMPLE
G.f.: A(x,y) = 1 + (3 + y)x + (45 + 12y + y^2)x^2 + (6687 + 801y + 39y^2 + y^3)x^3 +...
Triangle begins:
1;
3, 1;
45, 12, 1;
6687, 801, 39, 1;
10782369, 540720, 10764, 120, 1;
169490304819, 3499254081, 29275956, 129348, 363, 1;
25016281429306077, 206071208583660, 709664882337, 1321144632, 1459773, 1092, 1;
34185693516532070487615, 109444624780070083617, 150302858159634327, 115097787387369, 53628299415, 15815241, 3279, 1; ...
PROG
(PARI) {T(n, k)=polcoeff(polcoeff(exp(sum(m=1, n+1, (3^m+y)^m*x^m/m)+x*O(x^n)), n, x), k, y)}
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Paul D. Hanna, Feb 04 2009
STATUS
approved