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Difficult Sequence (Posted on 2003-10-18) Difficulty: 5 of 5
What is the next number in the sequence? 21,45,66,102,115,171,?

  Submitted by Freddy Grants    
Rating: 3.6667 (9 votes)
Solution: (Hide)
the solution is 168. formula is n^2+integers ascending/descending from 20, depending on what n equals. for example. the 1st number equals 1^2+20. the 2nd, 2^2+20+21. 3rd = 3^2=20+19+18. 4th, 4^2+20+21+22+23, 5th= 5^2+20+19+18+17+16.odd bases you descend from 20, even bases you asecend from 20. so for the question mark, you would do 7^2+20+19+18+17+16+15+14=168

Comments: ( You must be logged in to post comments.)
  Subject Author Date
SolutionProblem SolutionK Sengupta2007-04-20 14:57:03
hard oneBilly Bob2004-03-28 15:00:03
re(2): An alternate approach - I think I got itDan2003-11-02 14:51:22
re: An alternate approach - I think I got itBrian Smith2003-10-27 10:46:37
HintFreddy Grants2003-10-25 10:13:03
Hint:Gamer2003-10-24 17:04:37
Questionhint?pleasance2003-10-24 07:28:54
Another approachManguexa2003-10-23 00:05:55
Odd/Even..Paul2003-10-22 19:40:14
StrangeFernando Baibich2003-10-22 15:07:46
re(2): An alternate approachBrian Smith2003-10-21 13:53:37
re: An alternate approachSilverKnight2003-10-21 13:31:52
An alternate approachBrian Smith2003-10-21 13:22:16
re: This one was tuff !!SilverKnight2003-10-21 11:11:38
This one was tuff !!Dan2003-10-21 10:15:42
solution? maybe not what he had in mind....SilverKnight2003-10-20 15:32:35
re(2): AARRGG..Fernando Baibich2003-10-20 15:28:27
re: AARRGG..Brian Smith2003-10-20 15:21:35
Some ThoughtsAARRGG..Paul2003-10-20 14:04:23
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