Next Number | 5 Sep 2009

Kshiteej

Which is the next number in below series.

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

shabbir

Looks like we would have OP as winner.

xpi0t0s

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

SaswatPadhi

Quote:

Originally Posted by xpi0t0s
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
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 ??

As you already said, we probably need some more terms ...

shabbir

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

xpi0t0s

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

that was nice xpi0t0s

neo_vi

The next number is 37. Am i right?

Kshiteej

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.

neo_vi

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)

Kshiteej Contributor
5Sep2009,10:29	#1
	Which is the next number in below series. 1, 2, 7, 12, 19, 42, ?

shabbir Go4Expert Founder
6Sep2009,11:29	#2
	Looks like we would have OP as winner.

xpi0t0s Mentor
6Sep2009,13:48	#3
	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^7-182x^6+10500x^5-252586x^4+2762303x^3-13306896x^2+24059196x-13272336

SaswatPadhi ~ Б0ЯИ Τ0 С0δЭ ~
6Sep2009,15:54	#4
	Quote: Originally Posted by xpi0t0s 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 Of course, any number can be the answer, for example 99, because these are the roots of the equation x^7-182x^6+10500x^5-252586x^4+2762303x^3-13306896x^2+24059196x-13272336 Yeah, but then how do we express the general term, say 'n'th term of the series ?? As you already said, we probably need some more terms ...

shabbir Go4Expert Founder
6Sep2009,16:59	#5
	Kshiteej can we have the answer of this so we can have the question for today.

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xpi0t0s Mentor
6Sep2009,23:51	#6
	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

neo_vi Invasive contributor
7Sep2009,10:03	#8
	The next number is 37. Am i right?

Kshiteej Contributor
7Sep2009,10:07	#9
	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.

neo_vi Invasive contributor
7Sep2009,10:18	#10
	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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