mersenneforum.org Smallest composite without known factors "stuck" on (10^79-181)%(10^79-1)/9
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 2020-09-01, 05:31 #1 jdcs   Sep 2019 810 Posts Smallest composite without known factors "stuck" on (10^79-181)%(10^79-1)/9 The "Smallest composite without known factors" on the status page often points to http://factordb.com/index.php?id=1100000000900935563, but that number is actually prime. Is it possible to fix that entry so that we can see the real smallest unfactored number?
 2020-09-01, 09:21 #2 kruoli     "Oliver" Sep 2017 Porta Westfalica, DE 2×7×29 Posts It thinks that 1551548344191988309623860115843108935500421 is a factor of that number for some reason. Maybe it thinks it is composite because it evaluates the expression to 1111111111111111111111111111111111111111111111111111111111111111111111111110931 and not 1111111111111111111111111111111111111111111111111111111111111111111111111111091?
 2020-09-01, 09:28 #3 retina Undefined     "The unspeakable one" Jun 2006 My evil lair 176C16 Posts There is a duplicate entry: http://factordb.com/index.php?id=1100000000902314000
 2020-09-01, 11:43 #4 JeppeSN     "Jeppe" Jan 2016 Denmark 22×41 Posts There must be or have been some inconsistence on how the precedence is when the parentheses are not explicit. If you type (10^79-181)%((10^79-1)/9) you come to the fully factored 79-digit composite number: http://factordb.com/index.php?id=1100000000900937469 If you type ((10^79-181)%(10^79-1))/9 you come to the 79-digit prime: http://factordb.com/index.php?id=1100000000902314000 Both these entries are entirely correct. However, the entry you link: http://factordb.com/index.php?id=1100000000900935563 seems to be a mix-up of the two interpretations. It has evaluated to "C" (composite). But when you click Show digits, you see the expansion for the 79-digit prime. I speculate that one piece of code in factordb sees the expression in one way, and another place sees it in the other way, and we have this mix-up. The schizophrenic entry needs to be removed, and (if not fixed already) the operator precedence convention must be consequent. /JeppeSN

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