a(n) = a(n-1) + 3*a(n-2) -2*a(n-3) - 2*a(n-4), where a(0) = 0, a(1) = 0, a(2) = 2, a(3) = 3.

Terms

a(0) =0a(1) =0a(2) =2a(3) =3a(4) =9a(5) =14a(6) =31a(7) =49a(8) =96a(9) =153a(10) =281a(11) =450a(12) =795a(13) =1277a(14) =2200a(15) =3541a(16) =5997a(17) =9666a(18) =16175a(19) =26097a(20) =43296a(21) =69905a(22) =115249a(23) =186178a(24) =305523a(25) =493749a(26) =807464a(27) =1305309a(28) =2129157a(29) =3442658