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 Kshiteej 5Sep2009 10:29

Next Number | 5 Sep 2009

Which is the next number in below series.

1, 2, 7, 12, 19, 42, ?

 shabbir 6Sep2009 11:29

Re: Next Number | 5 Sep 2009

Looks like we would have OP as winner. :D

 xpi0t0s 6Sep2009 13:48

Re: Next Number | 5 Sep 2009

Nothing found here:
http://www.research.att.com/~njas/se...lish&go=Search

Without commas this returns 432 pages of results; looked through the first few but there was nothing obvious.

So we need more terms to deduce the sequence.

Of course, any number can be the answer, for example 99, because these are the roots of the equation
x^7-182*x^6+10500*x^5-252586*x^4+2762303*x^3-13306896*x^2+24059196*x-13272336

Re: Next Number | 5 Sep 2009

Quote:
 Originally Posted by xpi0t0s (Post 56939) Nothing found here: http://www.research.att.com/~njas/sequences/?q=1%2C2%2C7%2C12%2C19%2C42&sort=0&fmt=0&language= english&go=Search Without commas this returns 432 pages of results; looked through the first few but there was nothing obvious. So we need more terms to deduce the sequence.
Even I searched there, in vain :(

Quote:
 Originally Posted by xpi0t0s (Post 56939) Of course, any number can be the answer, for example 99, because these are the roots of the equation x^7-182*x^6+10500*x^5-252586*x^4+2762303*x^3-13306896*x^2+24059196*x-13272336
Yeah, but then how do we express the general term, say 'n'th term of the series ?? :undecided
As you already said, we probably need some more terms ... :thinking:

 shabbir 6Sep2009 16:59

Re: Next Number | 5 Sep 2009

Kshiteej can we have the answer of this so we can have the question for today.

 xpi0t0s 6Sep2009 23:51

Re: Next Number | 5 Sep 2009

Assuming that is enough to deduce the series, then using the same technique as before I get 113.
Code:

```1                                        2        1                                7        5        4                        12        5        0        -4                19        7        2        2        6        42        23        16        14        12        6 113        71        48        32        18        6```

 Seema786 7Sep2009 06:41

Re: Next Number | 5 Sep 2009

that was nice xpi0t0s

 neo_vi 7Sep2009 10:03

Re: Next Number | 5 Sep 2009

The next number is 37. Am i right?

 Kshiteej 7Sep2009 10:07

Re: Next Number | 5 Sep 2009

Hi all,
Consider alternative terms set 2 ie 2,12,42
12-2 = 10 = (2)^3 + 2
42-12 = 30 = (3)^3 + 3

Consider alternative terms set 1 ie. 1,7,19
7-1 = 6 = (2)^2 + 2
19-7= 12 = (3)^2 + 3

as the next number belongs to alternative set 1 ( because next numbers postion is odd)

next number should be 19 + (4)^2 + 4 = 39

 neo_vi 7Sep2009 10:18

Re: Next Number | 5 Sep 2009

I too thought in the same angle. But some thing went wrong

1, 2, 7, 12, 19, 42

The diff b/w 1st and third is 6 (7-1)

The diff b/w 5th and 3rd is 12 (19-7)

So,The diff b/w 7th and 5th should be 18 (37-19) which follows multiples of 6.

Similarly,
the diff b/w 4th and 2nd is 10 (12-2)

the diff b/w 6th and 4th is 30 (42-12)

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