a(n) = Sum_{i=0..n-1} a(i)*a(n-i) with a(0)=1, a(1)=6.

Terms

a(0) =1a(1) =6a(2) =6a(3) =42a(4) =114a(5) =654a(6) =2526a(7) =13506a(8) =61242a(9) =321558a(10) =1579830a(11) =8311578a(12) =42655938a(13) =226373406a(14) =1192341390a(15) =6391471794a(16) =34239385482a(17) =185275416102