a(n) = 7^n mod 3^n.

Terms

a(0) =0a(1) =1a(2) =4a(3) =19a(4) =52a(5) =40a(6) =280a(7) =1231a(8) =4243a(9) =3457a(10) =43882a(11) =11929a(12) =437797a(13) =407374a(14) =2851618a(15) =10395388a(16) =1023181a(17) =7162267a(18) =50135869a(19) =738371572a(20) =1681816603a(21) =1312363018a(22) =9186541126a(23) =1543668664a(24) =104948859475a(25) =452212479844