21242

Appears in sequences

• Numbers k such that sigma(k) = sigma(k+13).at n=9A015883
• Numbers k such that k and k^2 use only the digits 1, 2, 4, 5 and 6.at n=54A136988
• Sums of the antidiagonals of Sundaram's sieve (A159919).at n=37A159920
• Squarefree numbers k such that k^2 is abundant, and d^2 is nonabundant for any proper divisor d of k.at n=39A381741