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%I #18 Oct 11 2015 11:27:27
%S 4,6,9,10,16,25,45,48,50,64,86,122,192,256,289,314,326,448,562,578,
%T 706,722,729,794,842,1226,1346,1458,1514,1681,1754,1922,2186,2401,
%U 2566,2601,2916,3362,3481,3866,3986,4046,4096,4274,4852,5043,5186,5414
%N Values of n such that sigma(n!) mod sigma(n) is not 0.
%C Subsequence of A002808.
%C Motivation was the investigation of sum of divisors of n! in terms of sum of divisors of n.
%C Obviously, a(n) cannot be a prime number, although it can be a semiprime number.
%C Is this sequence infinite?
%F A066247(a(n)) = 1.
%F A000005(a(n)) > 2.
%F A001222(a(n)) > 1.
%e a(1) = 4 because sigma(4!) mod sigma(4) = 60 mod 7 = 4.
%e a(2) = 6 because sigma(6!) mod sigma(6) = 2418 mod 12 = 6.
%e a(3) = 9 because sigma(9!) mod sigma(9) = 1481040 mod 13 = 2.
%o (PARI) for(n=1, 1e30, if( sigma(n!) % sigma(n) != 0 , print1(n", ")))
%Y Cf. A062569, A000203.
%K nonn
%O 1,1
%A _Altug Alkan_, Oct 03 2015
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