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

Terms

a(0) =0a(1) =1a(2) =1a(3) =8a(4) =17a(5) =81a(6) =224a(7) =881a(8) =2737a(9) =9928a(10) =32481a(11) =113761a(12) =380800a(13) =1313441a(14) =4441121a(15) =15215688a(16) =51677297a(17) =176530481a(18) =600723424a(19) =2049428881a(20) =6980069457a(21) =23799693448a(22) =81088954561a(23) =276417142721a(24) =941948403200