56419

Appears in sequences

• Numbers k such that k and k+1 have the same sum of squarefree divisors, or sqf(k) = sqf(k+1), where sqf(k) = A048250(k).at n=18A063964
• Numbers k such that sigma(triangular(k)) = sigma(k)^2.at n=11A232355
• Composite numbers k such that sigma(k + sigma(k)) = 2*sigma(k).at n=39A246858
• Numbers k with the property that it is possible to write the base 2 expansion of k as concat(a_2,b_2), with a_2>0 and b_2>0 such that, converting a_2 and b_2 to base 10 as a and b, we have sigma(a + b) = sigma(k).at n=19A258843
• Numbers k such that abs(A328258(k)) = abs(A328258(k+1)).at n=36A348586
• Number k such that A033634(k) = A033634(k+1).at n=19A349224