Consider a partitioning function P
k(n), which lists all the ways you can write a positive integer
n as the sum of
k other positive integers, where order doesn't matter. For example:
P
2(5) = { (1,4) , (2,3) }
P
3(5) = { (1,1,3) , (1,2,2) }
P
2(6) = { (1,5) , (2,4) , (3,3) }
For any given list, you can find the LCM of each individual partition, for example:
LCM(1,4) = 4
LCM(2,3) = 6
Those are all of the 2-partitions of 5, and the biggest LCM is 6. That is,
Max( LCM( P
2(5) ) ) = 6
For the sake of brevity, let's condense all of that into a single function:
a
k(n) = Max( LCM( P
k(n) ) )
In general, you would expect a
k(n) to get bigger as
n gets bigger, and much faster than the lower bound of
n-
k+1 guaranteed by the partition (1, 1, ...,
n-
k+1). The bigger
n is, the more ways there are to write it as the sum of smaller positive integers, and thus the more "chances" there are to have a big LCM. But it's not always the case that a
k(n) grows. For example:
a
2(5) = 6 ≥ 5 = a
2(6)
a
3(10) = 30 ≥ 21 = a
3(11)
So my questions are twofold:
- What is the asymptotic behavior of ak(n)? Is there a nice closed form expression?
- How often is it true that ak(n) ≥ ak(n+1)? If it only happens finitely many times, when is the last one?