a(n) = Sum_{j=1..n} Sum_{i=1..j} (i*j)^5.

Terms

a(0) =0a(1) =1a(2) =1057a(3) =68125a(4) =1399325a(5) =15227450a(6) =110102426a(7) =597639882a(8) =2621915850a(9) =9756511275a(10) =31839011275a(11) =93340522951a(12) =250280856007a(13) =622316813300