Michael J Swart
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 Jan 7 awarded Popular Question Dec 10 comment Proving $1+2^n+3^n+4^n$ is divisible by $10$ When a is divisible by 5 then a^4 isn't equivalent to 1 mod 5. But in this case it doesn't matter because we only consider 2^n, 3^n and 4^n right? Oct 9 awarded Commentator Oct 9 comment What is the meaning of a number's “representation” on Wolfram Alpha? I would argue it isn't a curious fact at all. I'd say that without any noticeable pattern, it's no more or less interesting than any other random expression that equates to the same value. Jan 30 comment Find five positive integers whose reciprocals sum to $1$ I wouldn't be surprised if a bright fifth grader came up with the trivial x=y=z=a=b=5. Then answer the next question with "No": x=y=z=a=6, b=3. That seems do-able for bright grade fives. Dec 9 awarded Nice Question Dec 7 awarded Benefactor Dec 6 awarded Promoter Oct 19 comment What's the General Expression For Probability of a Failed Gift Exchange Draw Also relevant: Integer sequence "Number of permutations with no hits on 2 main diagonals." oeis.org/A000316 Oct 19 awarded Editor Oct 19 comment What's the General Expression For Probability of a Failed Gift Exchange Draw See question text for a link to my blog post on this. Oct 19 revised What's the General Expression For Probability of a Failed Gift Exchange Draw Linked to a blog article about this problem Oct 19 comment What's the General Expression For Probability of a Failed Gift Exchange Draw Yep, the blog post goes live at noon today. When that happens, I'll do it :-) Oct 17 awarded Scholar Oct 17 accepted What's the General Expression For Probability of a Failed Gift Exchange Draw Oct 17 comment What's the General Expression For Probability of a Failed Gift Exchange Draw This is brilliant, thanks so much. Can I quote your answer in a blog post? I'll be sure to provide links back. Oct 17 comment What's the General Expression For Probability of a Failed Gift Exchange Draw Didier, Being able to use "know" four times in a sentence. Very nice, I actually smiled at that. Oct 17 awarded Supporter Oct 17 comment What's the General Expression For Probability of a Failed Gift Exchange Draw Nice answer Ross, I'm also impressed by your math typography skills. Looks very professional. I'm not sure what the expression with e means (is that as n approaches infinity?) But you're right. The function is pretty close. Oct 17 comment What's the General Expression For Probability of a Failed Gift Exchange Draw @Didier, It's an English expression. I'm telling Charles that he helped a lot. And thanks for your link Didier.