OFFSET
1,2
MATHEMATICA
t[m_, n_] := t[m, n] = If[m == 1 || n == 1, 1, Sum[t[k, n], {k, m - 1}] * Sum[t[m, j], {j, n - 1}]]; Plus @@@ Table[t[d + 1 - j, j], {d, 12}, {j, d}] (* Ray Chandler, Dec 11 2006 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Leroy Quet, Nov 23 2006
EXTENSIONS
Extended by Ray Chandler, Dec 11 2006
STATUS
approved