G.f.: q-cosh(x) evaluated at q=-x.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =2a(5) =4a(6) =6a(7) =9a(8) =14a(9) =18a(10) =18a(11) =16a(12) =67a(13) =67a(14) =66a(15) =72a(16) =84a(17) =99a(18) =117a(19) =138a(20) =159a(21) =468a(22) =516a(23) =578a(24) =679a(25) =810a(26) =933a(27) =1018a(28) =1072a(29) =1138