Dirichlet convolution of b_n=1 with c_n=3^(n-1).

Terms

a(0) =1a(1) =4a(2) =10a(3) =31a(4) =82a(5) =256a(6) =730a(7) =2218a(8) =6571a(9) =19768a(10) =59050a(11) =177430a(12) =531442a(13) =1595056a(14) =4783060a(15) =14351125a(16) =43046722a(17) =129146980a(18) =387420490a(19) =1162281262a(20) =3486785140a(21) =10460412256a(22) =31381059610a(23) =94143358444a(24) =282429536563a(25) =847289140888