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 Not a Prime (Posted on 2012-12-20)
Prove that 5100+575+550+525+1 is not a prime number.

 No Solution Yet Submitted by Danish Ahmed Khan Rating: 3.0000 (2 votes)

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 re: answer | Comment 3 of 6 |

I'd be interested in seeing how these factors were found. My factoring program found 3597751 and 28707251, but got only as far as 56531057 in trial divisors of the remaining 76379660648003781777292087596491819833721077266601195001, which is nowhere near the needed 4032808198751 for the next prime divisor.

But, BTW, the final "prime" factor listed, 4687045214139234043375683501, also fails the prime test, the P value being 60895742403057891673741119:

list
10   N=4687045214139234043375683501
20   for Dvsr=12345 to 99999
30     if N @ Dvsr = 0 then print Dvsr:cancel for:goto *Found
40     P=modpow(Dvsr,N-1,N)
50     if P<>1 then print "not prime":print Dvsr:print P:cancel for:goto *Npr
ime
60   next
65   print "couldn't prove"
70   *Found
80   *Nprime
90   end
OK
run
not prime
12345
60895742403057891673741119
OK

Edited on December 21, 2012, 12:11 am
 Posted by Charlie on 2012-12-21 00:05:37

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