Prove every number in the sequence 38, 381, 3811, 38111, 381111, ... is composite.
(In reply to
No proof but a pattern found by Charlie)
More analysis of the pattern
Every third one divisible by 3 is easy to see by adding the digits.
The one after that is always 37*103, 37*103003, 37*103003003, 37*103003003003,...
The one next is always 23*1657, 233*163567, 2333*16335667, 23333*1633356667, 233333*163333566667,...
Probably we can get a proof by the pattern of the latter to situations.
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Posted by chun
on 2017-06-30 09:42:22 |
re: No proof but a pattern found
