p-INVERT of (3n), where p(S) = 1 - S - S^2.

Terms

a(0) =3a(1) =24a(2) =162a(3) =1083a(4) =7260a(5) =48681a(6) =326406a(7) =2188536a(8) =14674041a(9) =98388840a(10) =659693103a(11) =4423214952a(12) =29657473194a(13) =198852130383