Related to 3-line Latin rectangles.

Terms

a(0) =1a(1) =-1a(2) =-1a(3) =2a(4) =49a(5) =629a(6) =6961a(7) =38366a(8) =-1899687a(9) =-133065253a(10) =-6482111309a(11) =-281940658286