OFFSET
1,6
COMMENTS
If m and n are coprime then a(m*n) >= a(m)*a(n). - Charlie Neder, Jun 11 2019
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..65537
Rémy Sigrist, Colored logarithmic scatterplot of the first 10000 terms (where the color is function of A000005(n))
EXAMPLE
For n = 6: w_6 takes the following values:
k w_6(k) Corresponding sets of divisors
-- ------ ------------------------------
0 1 {}
1 1 {1}
2 1 {2}
3 2 {1, 2}, {3}
4 1 {1, 3}
5 1 {2, 3}
6 2 {1, 2, 3}, {6}
7 1 {1, 6}
8 1 {2, 6}
9 2 {1, 2, 6}, {3, 6}
10 1 {1, 3, 6}
11 1 {2, 3, 6}
12 1 {1, 2, 3, 6}
>12 0 None
Hence a(6) = 2.
PROG
(PARI) a(n) = my (p=1); fordiv (n, d, p*=(1+'X^d)); vecmax(Vec(p))
CROSSREFS
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Jun 10 2019
STATUS
approved