[seqfan] Re: Subsets with prime sums
Michael Porter
ic_designer at verizon.net
Mon Oct 26 03:15:29 CET 2009
It seems like a good sequence to me.
It reminds me of the subset-sum problem: given a set of integers, find a subset that sums to a given integer.
http://en.wikipedia.org/wiki/Subset_sum_problem
- Michael
--- On Sat, 10/24/09, zak seidov <zakseidov at yahoo.com> wrote:
From: zak seidov <zakseidov at yahoo.com>
Subject: [seqfan] Re: Subsets with prime sums
To: "seqfaneu" <seqfan at seqfan.eu>
Date: Saturday, October 24, 2009, 8:52 AM
I didn't mention that
all subsets are of length n,
of course.
Sorry,
Zak
%N A1
> For each n, take n subsets of set 1..n^2.
> Then select subsets with prime sums.
> The sequence gives the
> numbers of such subsets for n=2,3,4,5,6.
--- On Sat, 10/24/09, zak seidov <zakseidov at yahoo.com> wrote:
> From: zak seidov <zakseidov at yahoo.com>
> Subject: [seqfan] Subsets with prime sums
> To: "seqfaneu" <seqfan at seqfan.eu>
> Date: Saturday, October 24, 2009, 11:31 AM
> Dear seqfans,
>
> Pending your
> comments/editings/approvals/rejections/more_terms...
>
> Thanks, Zak
>
> %S A1
> 4,26,444,11998,382716
>
> N A1
> For each n, take n subsets of set 1..n^2.
> Then select subsets with prime sums.
> The sequence gives the
> numbers of such subsets for n=2,3,4,5,6.
>
> %e A1
> n=2; a(2)=4 because there are four subsets of set {1,2,3,4}
> with prime sums:
> {1,2}=>3
> {1,4}=>5
> {2,3}=>5
> {3,4}=>7
>
> n=3; a(3)=26 because there are 26 subsets of set
> {1,2,3,4,5,6,7,8,9}
> {1,2,4},{1,2,8},{1,3,7},{1,3,9},{1,4,6},{1,4,8},{1,5,7},{1,7,9},{2,3,6},{2,3,8},{2,4,5},{2,4,7},{2,5,6},{2,6,9},{2,7,8},{2,8,9},{3,4,6},{3,5,9},{3,6,8},{3,7,9},{4,5,8},{4,6,7},{4,6,9},{4,7,8},{5,6,8},{6,8,9}
> with corresponding prime sums:
> {7,11,11,13,11,13,13,17,11,13,11,13,13,17,17,19,13,17,17,19,17,17,19,19,19,23}.
>
>
>
>
>
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>
> Seqfan Mailing list - http://list.seqfan.eu/
>
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