Number of disconnected 2-regular graphs on n vertices.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =1a(7) =1a(8) =2a(9) =3a(10) =4a(11) =5a(12) =8a(13) =9a(14) =12a(15) =16a(16) =20a(17) =24a(18) =32a(19) =38a(20) =48a(21) =59a(22) =72a(23) =87a(24) =109a(25) =129a(26) =157a(27) =190a(28) =229a(29) =272