Number of, not necessarily connected, regular simple graphs on n vertices with girth at least 7.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =2a(5) =1a(6) =2a(7) =2a(8) =3a(9) =2a(10) =3a(11) =2a(12) =3a(13) =2a(14) =4a(15) =3a(16) =5a(17) =4a(18) =6a(19) =5a(20) =7a(21) =7a(22) =9a(23) =9a(24) =13a(25) =12a(26) =18a(27) =16a(28) =41a(29) =21