%I #6 Jul 21 2019 18:52:25
%S 2,1,3,6,12,24,66,168,408,1014,2820,7656,20370,54096,154416,430710,
%T 1182504,3258816,9377922,26651328,74941608,210709446,612566616,
%U 1760983512,5017273554,14308403856,41833393896,121321861350,349444725492,1006135834560
%N a(n) = Sum_{i=1..floor((n+1)/4)} a(2*i-1) * a(n-2*i+1), with a(1)=2, a(2)=1, and a(3)=3.
%K nonn
%O 1,1
%A _Clark Kimberling_