77677

Appears in sequences

• Numbers having four 7's in base 10.at n=20A043520
• Composite numbers in A083137.at n=19A083138
• Palindromic brilliant numbers.at n=31A084350
• Near-repdigit semiprimes with 7 as repeated digit.at n=30A105988
• a(n) = 7*(10^(2*n+1) - 1)/9 - 10^n.at n=2A332176