Number of balanced symmetric graphs.

Terms

a(0) =1a(1) =2a(2) =4a(3) =6a(4) =10a(5) =22a(6) =38a(7) =102a(8) =182a(9) =574a(10) =1070a(11) =3798a(12) =7286a(13) =28894a(14) =57374a(15) =248502a(16) =506678a(17) =2384254a(18) =5007230a(19) =25247958a(20) =54311126a(21) =292500574a(22) =645652574a(23) =3680048502a(24) =8301671798a(25) =49967727934a(26) =115334270270a(27) =728281984278