2, 5, 12, 31, 86....
Series teasers are where you try to complete the sequence of a series of letters, numbers or objects.
What's the next number in this sequence?
2, 5, 12, 31, 86....
246
249
252
255
258
HintThree is a magic number!
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Answer
The answer is 249.
3^0 + 1 = 2
3^1 + 2 = 5
3^2 + 3 = 12
3^3 + 4 = 31
3^4 + 5 = 86
3^5 + 6 = 249
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Comments
jdnorway
May 03, 2002
| No, it's 249. |
chamber44
May 20, 2002
| I might have gotten the answer if it was listed. The CORRECT answer is 249. Quit posting without double checking your work. 3^3+4=31 NOT 86. And 3^4+5=86 NOT 248. JDNOWAY is right. |
mad-ade   
Jun 29, 2002
| I agree with the others this is a poor example of posting any old rubbish. |
(user deleted)
Aug 31, 2002
| It appears that cathalmcabe is well adept at posting any old rubbish. almost all his teasers i have seen up to date are either totally incorrect of contain disputable facts. |
mathemagician 
Apr 26, 2008
| 2, 5, 12, 31, 86, ...
The differences {a2-a1, a3-a2,a4-a3,a5-a4,...} = {3, 7, 19, 55,... }
Now, {b2-b1, b3-b2, b4-b3} =
{4, 12, 36, ... }
The last sequence is geometric with r=3, making the next term 108. Hence, b5-b4 = 108 ; b5= 163; a6-a5 = 163 , or a6 = 249. |
dalfamnest 
Aug 24, 2010
| With the correction, it's not so bad! I worthwhile little challenge. You can also get the next number using "x3 -1", "x3 -3", "x3 -5", etc  |
Quocalimar
Feb 16, 2013
| i did this to get 258.
the final number times 2, plus the number before it.
Odd coincidence, or did you plan that? |
spikethru4  
Feb 17, 2013
| Quocalimar, that doesn't even work. 2 x 86 + 31 = 203. Neither does it hold for the other numbers in the sequence.
Or am I misunderstanding you completely? |
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