a(0)=0; a(1)=1; a(2n) = 4*Sum_{k=0..n} a(2k-1); a(2n+1) = a(2n) + a(2n-1).

Terms

a(0) =0a(1) =1a(2) =4a(3) =5a(4) =24a(5) =29a(6) =140a(7) =169a(8) =816a(9) =985a(10) =4756a(11) =5741a(12) =27720a(13) =33461a(14) =161564a(15) =195025a(16) =941664a(17) =1136689a(18) =5488420a(19) =6625109a(20) =31988856a(21) =38613965a(22) =186444716a(23) =225058681a(24) =1086679440a(25) =1311738121a(26) =6333631924a(27) =7645370045a(28) =36915112104a(29) =44560482149