Pell numbers (A000129) minus Lucas numbers beginning at 2 (A000032).

Terms

a(0) =-2a(1) =0a(2) =-1a(3) =1a(4) =5a(5) =18a(6) =52a(7) =140a(8) =361a(9) =909a(10) =2255a(11) =5542a(12) =13538a(13) =32940a(14) =79939a(15) =193661a(16) =468625a(17) =1133118a(18) =2738432a(19) =6615760a(20) =15979301a(21) =38589489a(22) =93182755a(23) =224994602a(24) =543236038a(25) =1311570360a(26) =3166544519a(27) =7644930841a(28) =18456845405a(29) =44559332298