74444444447
domain: N
Appears in sequences
- Primes which are a sandwich of numbers made of only one digit between two 7's.at n=11A068688
- Smallest palindromic prime containing exactly n 4's.at n=8A083975
- Palindromic primes in which all internal digits are 4.at n=2A108841
- a(n) is the smallest 2*n + 1 digit prime consisting of a string of 2*n - 1 identical digits d sandwiched between two same digits different from d, or -1 if no such prime exists.at n=4A385144