a(n) = least k such that GCD of sigma(k) = A000203(k) and phi(k) = A000010(k) equals n-th primorial = A002110(n).

A081397

a(n) = least k such that GCD of sigma(k) = A000203(k) and phi(k) = A000010(k) equals n-th primorial = A002110(n).

Terms

    a(0) =3a(1) =14a(2) =488a(3) =16072a(4) =284229a(5) =29221621a(6) =25014312576

External references