23435953128domain: NAppears in sequencesTriangle read by rows: T(n,k) is the number of n X n matrices of rank k over F_2.at n=31A286331Triangular array read by rows. T(n,k) is the number of n X n matrices T over GF(2) such that there are exactly 2^k vectors v in GF(2)^n with Tv=v, n>=0, 0<=k<=n.at n=32A379105