reviewed
approved
proposed
editing
a(n) = n * A055231(n). - Amiram Eldar, Sep 01 2023
Cf. A055231, A087320, A001694, A086463.
Cf. A087320, A001694, A086463.
Sum_{k=1..n} a(k) ~ c * n^3, where c = (Pi^2/18) * Product_{p prime} (1 - 2/p^2 + 2/p^4 - 1/p^5) = 0.2165355664... . - Amiram Eldar, Nov 19 2022