A025269 a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5.

2, 1, 1, 1, 6, 27, 122, 555, 2530, 11564, 52994, 243467, 1121292, 5176432, 23952042, 111076279, 516217844, 2404051080, 11218106730, 52447788512, 245659502752, 1152673780946, 5417690242696, 25505048506311, 120257626246616, 567864679387562