G.f.: x*(1-x^2)*(x^4+x^3-x^2+x+1) / (x^8-4*x^6-x^4-4*x^2+1).

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =4a(5) =11a(6) =16a(7) =49a(8) =72a(9) =214a(10) =319a(11) =947a(12) =1408a(13) =4187a(14) =6223a(15) =18502a(16) =27504a(17) =81769a(18) =121552a(19) =361379a(20) =537196a(21) =1597106a(22) =2374129a(23) =7058377a(24) =10492416a(25) =31194361a(26) =46371025a(27) =137862866a(28) =204935836a(29) =609282227