Number of alternating polynomials of degree 3n in GF(2)[X], n>0.

Terms

a(0) =2a(1) =0a(2) =2a(3) =2a(4) =4a(5) =6a(6) =12a(7) =20a(8) =38a(9) =66a(10) =124a(11) =224a(12) =420a(13) =774a(14) =1456a(15) =2720a(16) =5140a(17) =9690a(18) =18396a(19) =34918a(20) =66576a(21) =127038a(22) =243148a(23) =465920a(24) =894784a(25) =1720530a(26) =3314018a(27) =6390930a(28) =12341860a(29) =23860200