View Single Post
Old 2020-09-01, 08:43   #1
enzocreti
 
Mar 2018

2·5·53 Posts
Default ...factorial(n) plus/minus 1 is semiprime

Is there an Oeis sequence dedicated to numbers n such that n!+1 and n!-1 are both semiprime? An example is 20970


Infact 20970!+1 is semiprime and also 20970!-1 is semi prime




No the example is wrong

Last fiddled with by enzocreti on 2020-09-01 at 08:46
enzocreti is offline   Reply With Quote