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

Terms

a(0) =1a(1) =3a(2) =4a(3) =10a(4) =14a(5) =34a(6) =48a(7) =116a(8) =164a(9) =396a(10) =560a(11) =1352a(12) =1912a(13) =4616a(14) =6528a(15) =15760a(16) =22288a(17) =53808a(18) =76096a(19) =183712a(20) =259808a(21) =627232a(22) =887040a(23) =2141504a(24) =3028544a(25) =7311552a(26) =10340096a(27) =24963200a(28) =35303296a(29) =85229696