a(n) is the number of graceful graphs with n edges and round(sqrt(3n+9/4)) vertices.

Terms

a(0) =1a(1) =2a(2) =1a(3) =8a(4) =4a(5) =1a(6) =44a(7) =16a(8) =4a(9) =482a(10) =216a(11) =52a(12) =12a(13) =5604a(14) =1890a(15) =432a(16) =84a(17) =130712a(18) =49440a(19) =12132a(20) =3016a(21) =452a(22) =64a(23) =874522a(24) =238464a(25) =48904a(26) =9304a(27) =960a(28) =320a(29) =11115400