# Writing formulas

• Aug 23rd 2010, 10:51 AM
najios1
Writing formulas
I have a set of sequence numbers beginning from 11 to 26.
n and m are variables.
n min = 11
n max = 19
or n = 11, 12…19
Pattern;
n will always going to add 7 elements to it
m will always have 8 elements
Example :
If n = 11 then m = 19,20……26
If n = 12 then m = 11, 20,21…26
If n = 13 then m = 11,12,21,22…26
If n = 14 then m = 11,12,13,22,23..26
If n = 15 then m= 11,12..14,23,24..26
How do you write this into a formula..?
• Aug 23rd 2010, 08:06 PM
Quote:

Originally Posted by najios1
I have a set of sequence numbers beginning from 11 to 26.
n and m are variables.
n min = 11
n max = 19
or n = 11, 12…19
Pattern;
n will always going to add 7 elements to it
m will always have 8 elements
Example :
If n = 11 then m = 19,20……26
If n = 12 then m = 11, 20,21…26
If n = 13 then m = 11,12,21,22…26
If n = 14 then m = 11,12,13,22,23..26
If n = 15 then m= 11,12..14,23,24..26
How do you write this into a formula..?

my stab at it

Let
${n_i} = i$ for $11 \leq i \leq 26$

then $m = n_{11} ... n_{i-2}, n_{i-1} \cup {n_{i+8}, ... n_{26} }$

EDIT:// afterthought
Let
$N = n_{i} .. n_{i+7}.
$

then
$
m = n_{11}, n_{12} ... n_{26} / N
$
• Aug 24th 2010, 02:33 AM
najios1

Thank you for the formula.

Can you explain further or elaborate on the 2nd equation (EDIT version afterthought) as I'm not getting it.

Thanks again.
• Aug 24th 2010, 03:54 PM
Quote:

Originally Posted by najios1

Thank you for the formula.

Can you explain further or elaborate on the 2nd equation (EDIT version afterthought) as I'm not getting it.

Thanks again.

I'll be happy to elaborate.
I should have decided to let O = 11, 12, 13, ... 26, for clarity. (11-26)
m is then O ''minus'' N. (denoted by the slash in set theory)

Consider the case n=14, then m = 11, 12, 13, 22 -26. but what is this, really? Well, m is a set containing all the numbers from 11 - 26 EXCEPT the numbers 14 - 21.

what is 14 in this case? i
what is 21 in this case? 14 + 7 = i + 7

If you have any further questions, don't hesitate to ask.