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Number sequence

What number is next in this series?
3465
4095
4725
5355
5775
5985
6435

Comments

( 6 comments — Leave a comment )
bohemiancoast
Jun. 6th, 2010 10:03 am (UTC)
Hmm. 6615?
drplokta
Jun. 6th, 2010 11:20 am (UTC)
Looks like, but I had to Google it.
bohemiancoast
Jun. 6th, 2010 01:55 pm (UTC)
What I mean is, I think it is *quite likely* to be 6615, but that's on the basis of noting a pattern that applies to some but not all of the other numbers.
nwhyte
Jun. 8th, 2010 11:01 am (UTC)
It is indeed 6615 - odd numbers with 24 factors - what alternative patterns did you think of?
bohemiancoast
Jun. 10th, 2010 08:31 pm (UTC)
Ah, yes, that makes sense. I factored the numbers, but didn't think to count factors. And many of the numbers are of the form

x * 15 * 21 (for 11, 13, 17, 19) though the others aren't...

and 6615 is 21 x 15 x 21 (or 3^3*5*7^2)

I will grant you that this is not a perfect approach. Hence the question mark.

I am now quite surprised that I managed to factor all the numbers without checking the number of factors or considering that the large number of odd factors might be relevant.
ice_hesitant
Jun. 7th, 2010 01:39 am (UTC)
6435+450+240=7125
( 6 comments — Leave a comment )

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