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From: Richard Ashbery <basura@invalid.addr.uk>
Newsgroups: comp.sys.acorn.programmer
Subject: Re: Specific numbers but in a random sequence
Date: Sat, 22 Jun 2019 16:46:35 +0100
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In article <qel12p$ibq$1@dont-email.me>,
   druck <news@druck.org.uk> wrote:
> On 21/06/2019 22:27, Gavin Crawford wrote:
> > Richard Ashbery <basura@invalid.addr.uk> Wrote in message:

[snip]

3,4,5,6,8,9,10,12,15,18,20,24,30,36,45,60,90,120I would like to be
able to use these variables in a random sequence.

> > Why not put them into an array and use a random number to choose
> >   the array index.

> Yes, and make sure you seed the random number generator, or it may 
> always go through the same pseudo random sequence each time its run.

> IIRC to seed do RND(-TIME) before any other call to RND.

Not quite there yet - if I use the following...

DIM array%(18)
array%() = 3,4,5,6,8,9,10,12,15,18,20,24,30,36,45,60,90,120
y = RND(-TIME)
FOR loop = 1 TO 5
FOR I% = 0 TO 18
PRINT array%(RND(I%))
NEXT I%
NEXT loop

90 random numbers gives poor distribution:

3 x10
4 x14
5 x16
6 x8
8 x9
9 x4
10 x6
12 x3
15 x2
18 x3
20 x7
24 x7
30 x2
36 none
45 none
60 x2
90 none
120 x1

5 is repeated 3 times in a row. 

Is there any way of improving it?

Richard