A343734 Highly composite 5-rough numbers: numbers that are divisible by neither 2 nor 3 whose number of divisors reaches a record.
1, 5, 25, 35, 175, 385, 1225, 1925, 5005, 13475, 25025, 85085, 175175, 425425, 1616615, 2977975, 8083075, 32757725, 37182145, 56581525, 185910725, 622396775, 929553625, 1301375075, 4647768125, 5391411025, 14315125825, 26957055125, 37739877175, 134785275625
Offset: 1
Keywords
Examples
number of
divisors
n a(n) prime factorization of a(n) of a(n)
-- ----- ---------------------------- ---------
1 1 - 1
2 5 5 2
3 25 5^2 3
4 35 5 * 7 4
5 175 5^2 * 7 6
6 385 5 * 7 * 11 8
7 1225 5^2 * 7^2 9
8 1925 5^2 * 7 * 11 12
9 5005 5 * 7 * 11 * 13 16
10 13475 5^2 * 7^2 * 11 18
11 25025 5^2 * 7 * 11 * 13 24
12 85085 5 * 7 * 11 * 13 * 17 32
Links
- Amiram Eldar, Table of n, a(n) for n = 1..208