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 Difficult Sequence (Posted on 2003-10-18)
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

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 Subject Author Date Problem Solution K Sengupta 2007-04-20 14:57:03 hard one Billy Bob 2004-03-28 15:00:03 re(2): An alternate approach - I think I got it Dan 2003-11-02 14:51:22 re: An alternate approach - I think I got it Brian Smith 2003-10-27 10:46:37 Hint Freddy Grants 2003-10-25 10:13:03 Hint: Gamer 2003-10-24 17:04:37 hint? pleasance 2003-10-24 07:28:54 Another approach Manguexa 2003-10-23 00:05:55 Odd/Even.. Paul 2003-10-22 19:40:14 Strange Fernando Baibich 2003-10-22 15:07:46 re(2): An alternate approach Brian Smith 2003-10-21 13:53:37 re: An alternate approach SilverKnight 2003-10-21 13:31:52 An alternate approach Brian Smith 2003-10-21 13:22:16 re: This one was tuff !! SilverKnight 2003-10-21 11:11:38 This one was tuff !! Dan 2003-10-21 10:15:42 solution? maybe not what he had in mind.... SilverKnight 2003-10-20 15:32:35 re(2): AARRGG.. Fernando Baibich 2003-10-20 15:28:27 re: AARRGG.. Brian Smith 2003-10-20 15:21:35 AARRGG.. Paul 2003-10-20 14:04:23

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