21161304

Appears in sequences

• Numbers k such that both k and sigma(k)=A000203(k) are powerful, i.e., are terms of A001694.at n=23A337044
• Indecomposable sigma-powerful numbers: powerful numbers k such that sigma(k) is also powerful, but restricted to terms that are not the product of 2 terms > 1 of A337044.at n=15A337045