Number of ways of partitioning n points on a circle into subsets only of sizes 2 and 3.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =2a(5) =5a(6) =8a(7) =21a(8) =42a(9) =96a(10) =222a(11) =495a(12) =1177a(13) =2717a(14) =6435a(15) =15288a(16) =36374a(17) =87516a(18) =210494a(19) =509694a(20) =1237736a(21) =3014882a(22) =7370860a(23) =18059899a(24) =44379535a(25) =109298070a(26) =269766655a(27) =667224480a(28) =1653266565a(29) =4103910930