p-INVERT of (0,1,0,1,0,1,...), where p(S) = (1 - 3 S)^2.

Terms

a(0) =6a(1) =27a(2) =114a(3) =459a(4) =1788a(5) =6804a(6) =25440a(7) =93825a(8) =342258a(9) =1237329a(10) =4439778a(11) =15829992a(12) =56135274a(13) =198125703a(14) =696387570a(15) =2438803863a(16) =8513220696a(17) =29631246012a(18) =102865720452a(19) =356257472589