Number of strings over Z_3 of length n with trace 0 and subtrace 1.

Terms

a(0) =0a(1) =0a(2) =0a(3) =6a(4) =30a(5) =90a(6) =252a(7) =756a(8) =2268a(9) =6642a(10) =19602a(11) =58806a(12) =176904a(13) =530712a(14) =1592136a(15) =4780782a(16) =14351094a(17) =43053282a(18) =129146724a(19) =387440172a(20) =1162320516a(21) =3486843450a(22) =10460294154a(23) =31380882462a(24) =94143001680a(25) =282429005040a(26) =847287015120