a(n) = n*(2*n^8 + 84*n^6 + 798*n^4 + 1636*n^2 + 315)/2835.

Terms

a(0) =0a(1) =1a(2) =18a(3) =163a(4) =996a(5) =4645a(6) =17718a(7) =57799a(8) =166344a(9) =432073a(10) =1030490a(11) =2286955a(12) =4772780a(13) =9446125a(14) =17852030a(15) =32398735a(16) =56730512a(17) =96220561a(18) =158611106a(19) =254831667a(20) =400030580a(21) =614859189a(22) =927052742a(23) =1373356887a(24) =2001853784a(25) =2874747225a(26) =4071671786a(27) =5693596923a(28) =7867403068a(29) =10751213181