a(n) has generating function 1/((1-x)^k*(1-x^2)^(k*(k-1)/2)) for k=8.

Terms

a(0) =1a(1) =8a(2) =64a(3) =344a(4) =1744a(5) =7400a(6) =29632a(7) =106808a(8) =366088a(9) =1168008a(10) =3570240a(11) =10347864a(12) =28915056a(13) =77493096a(14) =201249216a(15) =505130808a(16) =1233655332a(17) =2927916264a(18) =6784208704a(19) =15338678264a(20) =33950726992a(21) =73557910088a(22) =156378379456a(23) =326236930136a(24) =669101503096