67666domain: NAppears in sequencesSmallest multiple of A047201(n) (i.e., numbers not divisible by 5) with only digits 6 and 7.at n=36A124476Numbers k such that k and k^2 use only the digits 4, 5, 6, 7 and 8.at n=15A137140Numbers which have only digits 6 and 7 in base 10.at n=38A256292