Repeat Pell numbers A000129.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =2a(5) =2a(6) =5a(7) =5a(8) =12a(9) =12a(10) =29a(11) =29a(12) =70a(13) =70a(14) =169a(15) =169a(16) =408a(17) =408a(18) =985a(19) =985a(20) =2378a(21) =2378a(22) =5741a(23) =5741a(24) =13860a(25) =13860a(26) =33461a(27) =33461a(28) =80782a(29) =80782