a(0)=1, a(n) = 3*a(n-1) + n + 1.

Terms

a(0) =1a(1) =5a(2) =18a(3) =58a(4) =179a(5) =543a(6) =1636a(7) =4916a(8) =14757a(9) =44281a(10) =132854a(11) =398574a(12) =1195735a(13) =3587219a(14) =10761672a(15) =32285032a(16) =96855113a(17) =290565357a(18) =871696090a(19) =2615088290a(20) =7845264891a(21) =23535794695a(22) =70607384108a(23) =211822152348a(24) =635466457069