A374170 a(n) is the least nonsquare k such that sigma_n(k) divides sigma_2n(k).

20, 20, 6050, 7203

Offset: 1

Author

Mohammed Yaseen, Jun 30 2024

Keywords

• nonn
• more

Comments

a(1) = A227771(1); a(2) = A046871(5).

a(5) > 10^9 if it exists.

a(6) = 17328, a(7) = 50, a(13) = 761378.

Crossrefs

Cf. A020487, A227771, A046871.

Programs

PARI

a(n) = my(k=1, f=factor(k)); while (issquare(k) || (sigma(f, 2*n) % sigma(f, n)), f=factor(k++)); k; \\ Michel Marcus, Jun 30 2024