%I #7 Jun 12 2024 17:37:29
%S 1,2,6,30,190,1547,15106,173502,2286648,34053437,565424068,
%T 10358963615,207582616995,4516836844067,106059101583274,
%U 2673073911292478,71978776046880670,2062324447652722085,62647209605811093549,2011144064488835839006,68034719732835699646658
%N a(n) = A050446(n, n) = A050447(n, n).
%F a(n) = A373660(n, 0).
%o (Python)
%o from functools import cache
%o @cache
%o def T(n, k):
%o return T(n, k - 1) + sum(T(2 * j, k - 1) * T(n - 1 - 2 * j, k)
%o for j in range(1 + (n - 1) // 2)) if k > 0 else 1
%o def a(n): return T(n, n)
%o print([a(n) for n in range(21)])
%Y A050446, A050447, A373660.
%K nonn
%O 0,2
%A _Peter Luschny_, Jun 12 2024