number of partitions of n into positive integers.

galactus

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I was wondering if anyone knows if there's a formula to find the number of partitions of a number n. pka?.

I found a formula for the Bell number. Which gives the number of ways of partitioning a set of n objects into subsets.

For instance {1,2,3} has 5 since we have

{1,2,3}, {1,2}{3}, {1,3}{2}, {2,3}{1}, {1}{2}{3}

The formula is \(\displaystyle \L\\\frac{1}{e}\sum_{k=1}^{\infty}\frac{k^{n-1}}{(k-1)!}\)


I found some references to the number of ways to partition a number n into a sum of positive integers, but no formula.

For instance, 5 has 7 partitions:

5=4+1=3+2=3+1+1=2+2+1=2+1+1+1=1+1+1+1+1

Is there a general formula to find the number of ways a number can be partitioned this way?.

I found a clue which says the generating function for the number of partitions of n into distinct integers is \(\displaystyle \L\\(1+x)(1+x^{2})(1+x^{3})..........\). But, What about it?.

I just thought this was interesting to explore.
 
Chapter six if Ivan Niven’s MATHEMATICS OF CHOICE is devoted to the topic partitions of an integer. In chapter seven he go into how to use generating polynomials for that purpose.
 
OK, pka. Thanks. I will look into that book. I am sure they have it on Amazon. If it's not too much, I may buy it.
 
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