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A308608
For any n > 0 and k >= 0, let w_n(k) be the number of ways to write k as a sum of distinct divisors of n; a(n) = max_{k >= 0} w_n(k).
1
1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 6, 1, 1, 1, 2, 1, 6, 1, 1, 1, 1, 1, 8, 1, 1, 1, 4, 1, 5, 1, 1, 2, 1, 1, 11, 1, 1, 1, 1, 1, 5, 1, 3, 1, 1, 1, 36, 1, 1, 2, 1, 1, 4, 1, 1, 1, 3, 1, 32, 1, 1, 1, 1, 1, 4, 1, 7, 1, 1, 1, 28, 1, 1
OFFSET
1,6
COMMENTS
If m and n are coprime then a(m*n) >= a(m)*a(n). - Charlie Neder, Jun 11 2019
LINKS
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
Sequence in context: A340827 A360119 A033630 * A371213 A323719 A220122
KEYWORD
nonn
AUTHOR
Rémy Sigrist, Jun 10 2019
STATUS
approved