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Old 2020-09-01, 08:43   #1
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
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