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

Terms

a(0) =0a(1) =1a(2) =73a(3) =1045a(4) =7445a(5) =35570a(6) =130826a(7) =399738a(8) =1063290a(9) =2539515a(10) =5564515a(11) =11362351a(12) =21875503a(13) =40068860a(14) =70321460a(15) =118921460a(16) =194681076a(17) =309689493a(18) =480223005a(19) =727832905a(20) =1080632905a(21) =1574809126a(22) =2256376958a(23) =3183210350a(24) =4427370350a(25) =6077760975a(26) =8243141751