login
a(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=2, a(2)=1, and a(3)=3.
1

%I #7 Jul 31 2019 03:03:20

%S 2,1,3,6,12,33,84,204,507,1410,3828,10185,27048,78720,222051,613770,

%T 1704360,4978050,14312460,40615440,115306545,341021994,994082808,

%U 2865120612,8271370236,24556630128,72215184450,210645965832,614238371328,1836536385786

%N a(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=2, a(2)=1, and a(3)=3.

%K nonn

%O 1,1

%A _Clark Kimberling_

%E Offset corrected and title improved by _Sean A. Irvine_, Jul 30 2019