T(n,k)=Number of idempotent n X n 0..k matrices of rank n-2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =0a(4) =1a(5) =27a(6) =0a(7) =1a(8) =69a(9) =282a(10) =0a(11) =1a(12) =123a(13) =1434a(14) =2050a(15) =0a(16) =1a(17) =195a(18) =4182a(19) =20810a(20) =12405a(21) =0a(22) =1a(23) =273a(24) =9762a(25) =103050a(26) =260235a(27) =67557a(28) =0a(29) =1