a(n) = Sum_{1 <= i < j <= n} j^3*i^3.

Terms

a(0) =0a(1) =0a(2) =8a(3) =251a(4) =2555a(5) =15055a(6) =63655a(7) =214918a(8) =616326a(9) =1561110a(10) =3586110a(11) =7612385a(12) =15139553a(13) =28506101a(14) =51229165a(15) =88438540a(16) =147420940a(17) =238291788a(18) =374813076a(19) =575377095a(20) =864177095a(21) =1272587195a(22) =1840775123a(23) =2619572626a(24) =3672629650a(25) =5078879650a(26) =6935344650a(27) =9360309933