
COMMENTS

Largest number k such that sigma(k) <= tau(k)^n.
a(4) >= 41936006482988380963200.
From Jon E. Schoenfield, Nov 01 2017: (Start)
a(5) >= 2812833572480164685801568964499317649172616193664000;
a(6) >= A002110(49)*2321816378289408000 = 1.934333...*10^107.
(End)


EXAMPLE

24 has 8 divisors (1, 2, 3, 4, 6, 8, 12, and 24), and their sum is 1 + 2 + 3 + 4 + 6 + 8 + 12 + 24 = 60, which does not exceed 8^2 = 64. Every number k > 24 has sigma(k) > tau(k)^2, so a(2) = 24.
