The number of elements in S_4\det^{-1}(n)/GL(4,Z), where we take det : M_{4 X 4} (Z) => Z.

Terms

a(0) =1a(1) =3a(2) =7a(3) =16a(4) =18a(5) =37a(6) =36a(7) =83a(8) =85a(9) =116a(10) =101a(11) =262a(12) =154a(13) =264a(14) =337a(15) =476a(16) =305a(17) =657a(18) =409a(19) =894a(20) =788a(21) =851a(22) =682a(23) =1778a(24) =1037a(25) =1338a(26) =1530a(27) =2123a(28) =1288a(29) =3006