The number of disconnected k-regular simple graphs on 2k+4 vertices.

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =3a(5) =3a(6) =5a(7) =5a(8) =7a(9) =9a(10) =11a(11) =13a(12) =18a(13) =21a(14) =26a(15) =33a(16) =40a(17) =49a(18) =61a(19) =73a(20) =89a(21) =110a(22) =131a(23) =158a(24) =192a(25) =230a(26) =274a(27) =331a(28) =392a(29) =468