a(n) = 1 + F(2*n+1) + (-1)^n*L(n).

Terms

a(0) =4a(1) =2a(2) =9a(3) =10a(4) =42a(5) =79a(6) =252a(7) =582a(8) =1645a(9) =4106a(10) =11070a(11) =28459a(12) =75348a(13) =195898a(14) =515073a(15) =1344906a(16) =3526786a(17) =9223895a(18) =24163596a(19) =63236638a(20) =165595269a(21) =433469962a(22) =1134942774a(23) =2971150995a(24) =7778845732a(25) =20364843314a(26) =53316562617a(27) =139583423242a(28) =365436006810a(29) =956720876191