Number of dissections of a polygon.

Terms

a(0) =1a(1) =4a(2) =12a(3) =43a(4) =143a(5) =504a(6) =1768a(7) =6310a(8) =22610a(9) =81752a(10) =297160a(11) =1086601a(12) =3991995a(13) =14732720a(14) =54587280a(15) =202997670a(16) =757398510a(17) =2834510744a(18) =10637507400a(19) =40023636310a(20) =150946230006a(21) =570534578704