Number of cubic residues mod 7^n.

Terms

a(0) =1a(1) =3a(2) =15a(3) =99a(4) =689a(5) =4817a(6) =33713a(7) =235987a(8) =1651903a(9) =11563315a(10) =80943201a(11) =566602401a(12) =3966216801a(13) =27763517603a(14) =194344623215