180689

Appears in sequences

• Numbers k such that R_k + 8 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=14A097685
• Numbers k such that k concatenated with k-1 gives the product of two numbers which differ by 7.at n=6A116152
• Numbers k such that k concatenated with k+5 gives the product of two numbers which differ by 5.at n=5A116193