93306domain: NAppears in sequencesNumber of idempotent n X n 0..5 matrices of rank n-1.at n=5A224330T(n,k)=Number of idempotent n X n 0..k matrices of rank n-1.at n=50A224333Number of idempotent 6X6 0..n matrices of rank 5.at n=4A224337