Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #8 Oct 30 2012 16:51:04
%S 4,90,560,4032,302400,34214400,415134720,5448643200,1162377216000,
%T 320118685286400,5792623828992000,110586454917120000,
%U 46833363657400320000,1034080669555399065600,23863400066663055360000,574489260864110592000000,14403266468807344128000000,10162944820390462016716800000
%N (n-2)!/n when an integer.
%C n divides (n-2)! for all composite n >= 6.
%e a(1) = 4 because 4!/6 = 4. That is, 6 divides 4!.
%e a(2) =90 because the next composite number after 6 is 8. 6!/8 = 90, which means 8 divides 6!
%t f[n_] := If[PrimeQ[n], 0, (n-2)!/n]; Select[Table[f[n], {n,30}], IntegerQ[#] && #>0&]
%Y Cf. A129906.
%K nonn
%O 1,1
%A _Geoffrey Critzer_, Oct 27 2012