34271domain: NAppears in sequencesNumber of 7 X 7 binary matrices with n ones, with no zero rows or columns, up to row and column permutation.at n=29A056079Odd numbers k for which 23 is the smallest positive i with Jacobi symbol J(i,k) != 1.at n=3A112079Numbers k such that 2*13^k - 1 is prime.at n=20A174153