a(n) = Sum_{i=1..n} binomial(i+1,2)^6.

Terms

a(0) =1a(1) =730a(2) =47386a(3) =1047386a(4) =12438011a(5) =98204132a(6) =580094436a(7) =2756876772a(8) =11060642397a(9) =38741283022a(10) =121395233038a(11) =346594833742a(12) =914464085783