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Go back or double (Posted on 2016-07-25) Difficulty: 2 of 5
1,2,4,3,6,5,10,7,14,8,16,9,18,11,22,12,24...

This sequence has simple rules with a major hint in the title.

Part 1) Determine the rule to extend the sequence.

Part 2) Find, with no aids beyond a simple calculator, the 1000th term of this sequence.

No Solution Yet Submitted by Jer    
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An uncertain shorthand for part II | Comment 3 of 5 |
Watching at https://oeis.org/A034701 I've noticed that: 

3 is the 4th term follow by its double 6

12 is the 16th term follow by its double 24

48 is the 64th term follow by its double 96

If this pattern holds the 1024th term is 768 follow by its double.
(if it do not hold trash this post)

Then going back: 
1022th term will be 767

1020th term will be: not 766 (because 766=383*2) but 765

1018th term will be: 764 (as 764=382*2=191*2*2: 382 will follow 191, then 764 is free to use)

1016th term will be 763

1014th term will be: not 762 (because 762=381*2) but 761

1012th term will be: not 760 (because 760=380*2=190*2*2=95*2; 190 will follow 95 and 760 will follow 380) but 759

1010th term will be: not 758 (because 758=379*2) but 757

1008th term will be: 756 (because 756=378*2=189*2*2; give 756 free to use)

1006th term will be: 755

1004th term will be: not 754 (because 754=377*2), but 753

1002th term will be: 752 (because 752=366*2=183*2*2; so remain free to use)

1000th term should then be: 751





  Posted by armando on 2016-07-26 04:22:07
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