Partitions Derived From Prime-Subset
Leroy Quet
qq-quet at mindspring.com
Sat Mar 27 02:06:00 CET 2004
I will just copy/paste my reply from the sci.math thread at:
http://groups.google.com/groups?dq=&hl=en&lr=&ie=UTF-8&threadm=40502848.204
0009%40cox.net&prev=
I wonder here on seq.fan about the sequence formed from the number of
distinct partitions.
Leroy
--
I wrote on sci.math (original post and reply):
> Let P be any subset of the primes.
> (example: P contains all primes of even-index,
> or those congruent to 1 (mod 6).)
>
> Let A be the set of positive integers: including 1 and every positive
> integer which is a multiple of only the primes in P, and A contains
> no member which is divisible by a prime not in P.
>
> Let B be the set of positive integers: including 1 and every positive
> integer which is a multiple of only the primes *not* in P, and B
> contains no member which is divisible by a prime *in* P.
>
> (Yes, there are positive integers in neither set, as long as P does
> not contain every prime.)
>
>
> Let g(x) be the number of distinct elements of A which are <= x,
> for x = a positive real.
>
>
> So then, for m = any positive integer:
>
> ---
> \
> / g(m/k)
> ---
> k=elements of B, k <= m
>
> always = m.
>
>
> In linear-mode:
>
> sum{k=elements of B, k<=m} g(m/k)
>
> always equals m.
>
>
> (Right?)
>
> thanks,
> Leroy Quet
Every sum of g(m/k)'s (written of most recently above)
represents a partition of m (where each g is a part in the partition).
I wonder how many *distinct* partitions of m are represented by sums of
g's.
(Each g-sum corresponds with a given subset P of the primes <= m.)
I get by-hand that the sequence begins:
1, 2, 3, 4, 5, 7,..
thanks,
Leroy Quet
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