Euler's totient function (n) is defined as the number of positive integers not exceeding n that are relatively prime to n, where 1 is counted as being relatively prime to all numbers. So, for example,
(20) = 8 because the eight integers 1, 3, 7, 9, 11, 13, 17, and 19 are relatively prime to 20. The table below shows values of
(n) for n
20.
n | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
![]() | 1 | 1 | 2 | 2 | 4 | 2 | 6 | 4 | 6 | 4 | 10 | 4 | 12 | 6 | 8 | 8 | 16 | 6 | 18 | 8 |
Euler's totient valence function v(n) is defined as the number of positive integers k such that (k) = n. For instance, v(8) = 5 because only the five integers k = 15, 16, 20, 24, and 30 are such that
(k) = 8. The table below shows values of v(n) for n
16. (For n not in the table, v(n) = 0.)
n | v(n) | k such that ![]() |
---|---|---|
1 | 2 | 1, 2 |
2 | 3 | 3, 4, 6 |
4 | 4 | 5, 8, 10, 12 |
6 | 4 | 7, 9, 14, 18 |
8 | 5 | 15, 16, 20, 24, 30 |
10 | 2 | 11, 22 |
12 | 6 | 13, 21, 26, 28, 36, 42 |
16 | 6 | 17, 32, 34, 40, 48, 60 |
Evaluate v(21000).