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Posted 10 Months, 3 Weeks ago
124C41
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Can someone put me out of my misery? What's the next number in this series: 1 4 16 64 4096 ... ?

I think I've seen this one a long time ago and I think it's sneaky. It does appear on a numerical sequences website but it's a horrible trig function and this was a question to a 6th grade class.

Apologies if this is well-known, I don't usually read this ng -

Derek Wills
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Posted 10 Months, 3 Weeks ago
paydayuscf
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2^0 2^2 2^4 2^6 2^12

Why does the exponent go from 6 to 12 when it had been increasing by 2?
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Posted 10 Months, 3 Weeks ago
jugherffere
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Well, dat's de question! If the last term had been 256 I wouldn't have insulted the readers of this ng by posing the question
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Posted 10 Months, 3 Weeks ago
imported_Bojan
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Well, as you know, *any* number could be the next one. But one possibility for what the question-setter has in mind is a alternating rule: multiply by 4, then square, then repeat. In which case the next 5 terms would be: 16384, 268435456, 1073741824, 1152921504606846976, 4611686018427387904.
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Posted 10 Months, 3 Weeks ago
ciproantib
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could be 4^7 (4^n, n contains no 'f'
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Posted 10 Months, 2 Weeks ago
Jim
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The trigonometric function you are looking for is listed in the Encyclopedia of Integer Sequences:
http://www.research.att.com/cgi-bin/access.cgi/as/njas/ sequences/eism... choice=2&sequence=A013149

Cheers!
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Posted 10 Months, 2 Weeks ago
quest2006
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One possible answer is, because 6 + 4 + 2 is 12 (as 4 + 2 + 0 is 6). Following this rule, the next number in the sequence would be:

2^22

Seems too twisted for my taste, though...
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Posted 10 Months, 2 Weeks ago
jugherffere
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Or, 4^0 4^1 4^2 4^3 4^6 4^12

Wouldn't that be 2^24 ?

Actually, I like that progression best, so far. The trig function Sreeram posted about MAY be what the original author intended, but for 6th grade, it seems a bit extreme! A semi-simple arithmetic progression of exponents would be more reasonable. As in the Fibonacci series, it needs a couple terms to start, then continues forever. For that matter, a Fibonacci series in the exponents would make another nice puzzle series...
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Posted 10 Months, 2 Weeks ago
imported_Adrian
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Trig function? It seems to be a progression of exponents.

1 = 2^0 4 = 2^2 16 = 2^4 64 = 2^6 4096 = 2^12
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Posted 10 Months, 2 Weeks ago
kdavis004
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I think that throwing away the signs is cheating, personally. 16 and -16 are different numbers. If you think they're the same, lend me 16 Euros, and I'll pay you back -16.
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Posted 10 Months, 2 Weeks ago
quest_marsman
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No... Err... let me double check my sanity... Hmmm, no, I still think it's 2^22

If you see it as powers of 4, then it would be 4^11 (or 2^22). The progression is: 2 (or 4) to the power of the sum of the last three exponents:

2^(12+6+4)
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