a(n) = (27^n - 9^n)/2 - 12^n + 6^n.

A342234

a(n) = (27^n - 9^n)/2 - 12^n + 6^n.

Terms

    a(0) =0a(1) =3a(2) =216a(3) =7965a(4) =243000a(5) =6903873a(6) =190505196a(7) =5192233245a(8) =140764942800

External references