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5, 9, 15, 21, 31, 37, 47......etc. Please give at least 3 more terms of this sequence. Thank you.

Guest Mar 1, 2017
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5, 9, 15, 21, 31, 37, 47......etc. Please give at least 3 more terms of this sequence. Thank you.

 

I have been thinking about this sequence for close to an hour, and I came up with this "fanciful" solution:

If we factor the non-prime terms we get this:

9 = 3 x 3 =3 + 3 + 3  

15 =3 x 5 =5 + 5 + 5

21 = 3 x 7 =7 + 7 + 7

From the above, I deduced that each term consists of: Prime number x 2 + All the ODD numbers from 1 upwards!!. So:

1st. term =2 x 2 + 1=5

2nd.term=3 x 2 + 3 =9

3rd term =5 x 2 + 5 =15...... and this HOLDS for all the terms given!. Therefore, the next 3 terms would be: 19 x 2 + 15 =53

       23 x 2 + 17 =63

       29 x 2 + 19 = 77.........etc., so that the whole sequence looks like this:

5, 9, 15, 21, 31, 37, 47, 53, 63, 77.....etc.

And that is my take on it!!.

Guest Mar 1, 2017

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