T(n,k)=Number of idempotent n X n -k..k matrices of rank n-1.

Terms

a(0) =1a(1) =1a(2) =10a(3) =1a(4) =26a(5) =75a(6) =1a(7) =42a(8) =399a(9) =500a(10) =1a(11) =58a(12) =927a(13) =5220a(14) =3125a(15) =1a(16) =74a(17) =1815a(18) =17380a(19) =64285a(20) =18750a(21) =1a(22) =106a(23) =2751a(24) =46884