Numerator of n*(n-1)*(n-2)/720.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =1a(6) =1a(7) =7a(8) =7a(9) =7a(10) =1a(11) =11a(12) =11a(13) =143a(14) =91a(15) =91a(16) =14a(17) =17a(18) =34a(19) =323a(20) =19a(21) =133a(22) =77a(23) =1771a(24) =253a(25) =115a(26) =65a(27) =195a(28) =273a(29) =609