2-part of number of graphs on n nodes.

Terms

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