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Next Number | 5 Sep 2009

Discussion in '$1 Daily Competition' started by Kshiteej, Sep 5, 2009.

  1. Kshiteej

    Kshiteej New Member

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    Which is the next number in below series.

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

    shabbir Administrator Staff Member

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    Looks like we would have OP as winner. :D
     
  3. xpi0t0s

    xpi0t0s Mentor

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    Nothing found here:
    http://www.research.att.com/~njas/s...19,42&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.

    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
     
  4. SaswatPadhi

    SaswatPadhi ~ Б0ЯИ Τ0 С0δЭ ~

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    Even I searched there, in vain :(

    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:
     
  5. shabbir

    shabbir Administrator Staff Member

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    Kshiteej can we have the answer of this so we can have the question for today.
     
  6. xpi0t0s

    xpi0t0s Mentor

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    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
    
     
  7. Seema786

    Seema786 New Member

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    that was nice xpi0t0s
     
  8. neo_vi

    neo_vi Member

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    The next number is 37. Am i right?
     
  9. Kshiteej

    Kshiteej New Member

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    Hi all,
    sorry for my late reply.
    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


    So the answer is 39.
     
  10. neo_vi

    neo_vi Member

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    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)
     
  11. naimish

    naimish New Member

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    Grrrrrrrrrrrrrrrrrr I hate mathematics :embarasse
     
  12. Kshiteej

    Kshiteej New Member

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    Your logic would be correct if the 6th number is 32 instead of 42 so that the diff b/w 6th and 4th is 20 (32-12) i.e then 2nd difference series will be 10,20,30 like first difference series 6,12,18.
     
  13. naimish

    naimish New Member

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    Bad Luck neo_vi, but nice try ;)
     

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