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Difficult Sequence (Posted on 2003-10-18) |
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What is the next number in the sequence?
21,45,66,102,115,171,?
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Submitted by Freddy Grants
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Rating: 3.6667 (9 votes)
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Solution:
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(Hide)
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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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