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%I #19 Jul 14 2020 07:04:28
%S 7,13,19,21,28,31,37,39,43,52,57,61,63,67,73,76,79,84,93,97,103,109,
%T 111,112,117,124,127,129,139,148,151,156,157,163,171,172,175,181,183,
%U 189,193,199,201,208,211,219,223,228,229,237,241,244,252
%N Numbers k such that sigma(k) == 2 mod 6.
%H Amiram Eldar, <a href="/A074628/b074628.txt">Table of n, a(n) for n = 1..10000</a>
%F A000203(n) mod 6 = 2.
%F {n: A084301(n) = 2}. - _R. J. Mathar_, May 19 2020
%e For k=39: sigma(39) = 1+3+13+39 = 56 = 6*9 + 2.
%t Select[Range[300],Mod[DivisorSigma[1,#],6]==2&] (* _Harvey P. Dale_, Nov 14 2014 *)
%o (PARI) isok(n) = ((sigma(n) % 6) == 2); \\ _Michel Marcus_, Dec 19 2013
%Y Cf. A000203, A072862, A074384, A074627, A074628, A074629, A074630.
%K easy,nonn
%O 1,1
%A _Labos Elemer_, Aug 26 2002
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