93957domain: NAppears in sequencesSmallest k for which k, 2k, ... nk all contain the digit 7.at n=7A039938a(n) is the number of 2 X 2 matrices with entries in {1, ..., n} that are not the product of two 2 X 2 positive integer matrices.at n=18A260550A039938 with duplicates removed.at n=7A285846