Number of vectors in {0..4}^n with sum divisible by 9.

Terms

a(0) =1a(1) =1a(2) =1a(3) =11a(4) =81a(5) =381a(6) =1673a(7) =8338a(8) =43585a(9) =220037a(10) =1086581a(11) =5401793a(12) =27090649a(13) =135792879a(14) =678626796a(15) =3389980516a(16) =16949548097a(17) =84773530931a(18) =423896384077