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

Terms

a(0) =4a(1) =13a(2) =44a(3) =147a(4) =488a(5) =1616a(6) =5344a(7) =17661a(8) =58348a(9) =192739a(10) =636620a(11) =2102688a(12) =6944828a(13) =22937405a(14) =75757420a(15) =250210275a(16) =826389232a(17) =2729379568a(18) =9014530520a(19) =29772975309a(20) =98333463212a(21) =324773375891