a(0)=0; a(1)=1; a(n) = a(n-1) + (3 + (-1)^n)*a(n-2)/2.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =4a(5) =6a(6) =14a(7) =20a(8) =48a(9) =68a(10) =164a(11) =232a(12) =560a(13) =792a(14) =1912a(15) =2704a(16) =6528a(17) =9232a(18) =22288a(19) =31520a(20) =76096a(21) =107616a(22) =259808a(23) =367424a(24) =887040a(25) =1254464a(26) =3028544a(27) =4283008a(28) =10340096a(29) =14623104