Differences of 0: 6!*Stirling2(n,6).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =720a(6) =15120a(7) =191520a(8) =1905120a(9) =16435440a(10) =129230640a(11) =953029440a(12) =6711344640a(13) =45674188560a(14) =302899156560