Number of 4-regular polyhedra with n nodes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =1a(6) =0a(7) =1a(8) =1a(9) =3a(10) =3a(11) =11a(12) =18a(13) =58a(14) =139a(15) =451a(16) =1326a(17) =4461a(18) =14554a(19) =49957a(20) =171159a(21) =598102a(22) =2098675a(23) =7437910a(24) =26490072a(25) =94944685a(26) =341867921a(27) =1236864842a(28) =4493270976a(29) =16387852863