(Terms in A028273)/2.

Terms

a(0) =2a(1) =3a(2) =13a(3) =4a(4) =17a(5) =5a(6) =133a(7) =74a(8) =294a(9) =207a(10) =32a(11) =6a(12) =501a(13) =38a(14) =1089a(15) =440a(16) =7a(17) =215a(18) =3146a(19) =1859a(20) =59a(21) =8a(22) =5005a(23) =1092a(24) =67a(25) =9a(26) =27599a(27) =19916a(28) =11466a(29) =5194