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Consecutive non-divisors (Posted on 2011-12-27) Difficulty: 4 of 5
A positive integer N is such that:

(i) N is divisible by all but three of the k positive integers 1, 2, 3, . . . , k; and:

(ii) Those three positive integers (that donít divide N) are consecutive.

(For example, if N=60 then the corresponding value of k is 10, since 7, 8, 9 doesn't divide 60.)

Determine (with proof) the maximum value of the positive integer k satisfying all the given conditions.

No Solution Yet Submitted by K Sengupta    
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N (spoiler) Comment 3 of 3 |
And by the way, if I am right up to now (always a risk), then the smallest N for which k assumes its maximum value is  2*2*3*5*11*13 = 8580.

8580 is divisible by 1,2,3,4,5,6,10,11,12 and 13, but not by 7, 8 or 9.

  Posted by Steve Herman on 2011-12-27 20:47:35
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