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%I #26 Sep 08 2022 08:46:10
%S 1,3,8,14,18,48,52,54,62,72,96,98,114,186,486,524,712
%N Numbers m such that 5^m - m is a semiprime.
%C There are no other known terms under 1000 - the only possible terms are 812 and 908. - _Carl Schildkraut_, Aug 21 2015
%e 1 is in this sequence because 5^1-1 = 2*2 is semiprime.
%e 18 is in this sequence because 5^18-18 = 199*19169332993 and these two factors are prime.
%t Select[Range[100], PrimeOmega[5^# - #]==2 &]
%o (Magma) IsSemiprime:=func<i | &+[d[2]: d in Factorization(i)] eq 2>; [m: m in [1..100] | IsSemiprime(s) where s is 5^m-m];
%o (PARI) isok(n)=bigomega(5^n - n)==2 \\ _Anders Hellström_, Aug 21 2015
%Y Cf. similar sequences listed in A252656.
%K nonn,more
%O 1,2
%A _Vincenzo Librandi_, Dec 20 2014
%E a(13)-a(17) from _Carl Schildkraut_, Aug 21 2015
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