Generalized Lucas numbers.

Terms

a(0) =1a(1) =0a(2) =5a(3) =6a(4) =21a(5) =40a(6) =93a(7) =190a(8) =396a(9) =796a(10) =1586a(11) =3108a(12) =6025a(13) =11552a(14) =21947a(15) =41346a(16) =77311a(17) =143580a(18) =265013a(19) =486398a(20) =888122a(21) =1613944a(22) =2920100a(23) =5261880a(24) =9445905a(25) =16897328a(26) =30127665a(27) =53552190a(28) =94915273a(29) =167771168