Number of disconnected regular simple graphs on n vertices with girth at least 7.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =2a(5) =1a(6) =2a(7) =1a(8) =2a(9) =1a(10) =2a(11) =1a(12) =2a(13) =1a(14) =3a(15) =2a(16) =4a(17) =3a(18) =5a(19) =4a(20) =6a(21) =6a(22) =8a(23) =8a(24) =11a(25) =11a(26) =14a(27) =15a(28) =19a(29) =20