a(n) = (1/3^n) * Sum_{k=0..n^3} ( (binomial(n^3, k) * 2^k) (mod 3^n) ).

Terms

a(0) =1a(1) =4a(2) =5a(3) =33a(4) =63a(5) =112a(6) =179a(7) =260a(8) =369a(9) =502a(10) =659a(11) =868a(12) =1098a(13) =1367a(14) =1703a(15) =2046a(16) =2457a(17) =2895a(18) =3392a(19) =3975a(20) =4591a(21) =5322a(22) =6069a(23) =6899a(24) =7807a(25) =8828a(26) =9836a(27) =10948a(28) =12290a(29) =13440