a(n) = T(3n+1), where T(n) are tribonacci numbers A000073.

A074581

a(n) = T(3n+1), where T(n) are tribonacci numbers A000073.

Terms

    a(0) =0a(1) =2a(2) =13a(3) =81a(4) =504a(5) =3136a(6) =19513a(7) =121415a(8) =755476a(9) =4700770a(10) =29249425a(11) =181997601a(12) =1132436852a(13) =7046319384a(14) =43844049029a(15) =272809183135

External references