a(n) = n^5*(7*n+5)/2.

Terms

a(0) =0a(1) =6a(2) =304a(3) =3159a(4) =16896a(5) =62500a(6) =182736a(7) =453789a(8) =999424a(9) =2007666a(10) =3750000a(11) =6603091a(12) =11073024a(13) =17822064a(14) =27697936a(15) =41765625a(16) =61341696a(17) =88031134a(18) =123766704a(19) =170850831a(20) =232000000a(21) =310391676a(22) =409713744a(23) =534216469a(24) =688766976a(25) =878906250a(26) =1110908656a(27) =1391843979