Number of disconnected 6-regular (sextic) graphs on n vertices.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =0a(10) =0a(11) =0a(12) =0a(13) =0a(14) =1a(15) =1a(16) =5a(17) =25a(18) =297a(19) =8199a(20) =377004a(21) =22014143a(22) =1493574756a(23) =114880777582