%I
%S 1,2,6,36,360,6480,220320,14541120,1890345600,487709164800,
%T 250682510707200,257200255985587200,527260524770453760000,
%U 2160713630509319508480000,17704887488393364052485120000
%N a(1) = 1, a(2) = 2; for n>2, a(n) = sum_{r=1..n} {sum of all previous terms taken r at a time}.
%F a(n)=(2^(n2)+2)*a(n1), n>3.  _Vladeta Jovovic_, Nov 17 2003
%e a(4) = [{a(1)} + {a(2)} + {a(3)}] + [{(a(1) + a(2)} + {a(1) + a(3)} + { a(2) + a(3)}] + [{a(1) + a(2) + a(3)}] = 36.
%Y Cf. A089985.
%K nonn
%O 1,2
%A _Amarnath Murthy_, Nov 14 2003
%E More terms from _Ray Chandler_, Nov 21 2003
