a(n) = 4*a(n-2) - 4*a(n-4) + 25*a(n-6).

Terms

a(0) =1a(1) =1a(2) =1a(3) =37a(4) =37a(5) =169a(6) =169a(7) =553a(8) =553a(9) =2461a(10) =2461a(11) =11857a(12) =11857a(13) =51409a(14) =51409a(15) =219733a(16) =219733a(17) =969721a(18) =969721a(19) =4285177a(20) =4285177a(21) =18755149a(22) =18755149a(23) =82122913a(24) =82122913a(25) =360600481a(26) =360600481a(27) =1582788997a(28) =1582788997a(29) =6941826889