a(n) = n^4*(n^7 + 1)/2.

Terms

a(0) =0a(1) =1a(2) =1032a(3) =88614a(4) =2097280a(5) =24414375a(6) =181399176a(7) =988664572a(8) =4294969344a(9) =15690533085a(10) =50000005000a(11) =142655842626a(12) =371504195712a(13) =896080211299