This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A098594 #19 Aug 13 2023 12:02:11
%S A098594 5,8,10,13,20,24,26,34,59,392
%N A098594 Numbers n such that n!-1 and n!+1 are both semiprime.
%C A098594 This sequence is formed of all those terms that appear in both A078778 and A078781.
%C A098594 a(11) >= 929. 929!-1 is semiprime, no factor of 929!+1 is known. - _Sean A. Irvine_, Mar 09 2013
%e A098594 10!+1 = 3628801 = 11*329891 and 10!-1 = 3628799 = 29*125131 so 10 is a member of the sequence.
%e A098594 464 is not a term since 464!-1=2828197538205421590987128183441789966021011*C996 is not a semiprime. - _Sean A. Irvine_, Mar 09 2013
%p A098594 out:=[]: for n from 1 to 60 do: a:=n!-1: b:=n!+1: if (bigomega(a)=2) and (bigomega(b)=2) then out:=[op(out),n]: print(n): fi: od: out;
%t A098594 Select[Range[35],PrimeOmega[#!+{1,-1}]=={2,2}&] (* The program generates the first 8 terms of the sequence. To generate more, increase the Range constant but the program may take a long time to run. *) (* _Harvey P. Dale_, Aug 13 2023 *)
%Y A098594 Cf. A078778, A078781.
%K A098594 hard,more,nonn
%O A098594 1,1
%A A098594 Mark Hudson (mrmarkhudson(AT)hotmail.com), Sep 17 2004
%E A098594 a(10) from _D. S. McNeil_, Sep 04 2011