%I A050226
%S A050226 1,4,5,15,42,44,47,121,336,340,347,930,2548,6937,6947,51322,379097,
%T A050226 379131,379133,2801205,20698345,56264090,56264197,152941920,152942012,
%U A050226 8350344420,61701166395,455913379395,455913379831,1239301050694
%N A050226 Sum of divisor function d(n) (A000005) up to n is divisible by n.
%D A050226 Julian Havil, "Gamma: Exploring Euler's Constant", Princeton University 
               Press, Princeton and Oxford, pp. 112-113, 2003.
%F A050226 Sum {1..n} d(n) = n*k, k is an integer, d(n) = number of divisors of 
               n..
%e A050226 For n = 15 the sum is 1 + 2 + 2 + 3 + 2 + 4 + 2 + 4 + 3 + 4 + 2 + 6 + 
               2 + 4 + 4 = 45 which is divisible by 15.
%t A050226 s = 0; Do[ s = s + DivisorSigma[ 0, n ]; If[ Mod[ s, n ] == 0, Print[ 
               n ] ], {n, 1, 2*10^9} ]
%Y A050226 Cf. A000005, A006218, A057494, A085567, A085829.
%Y A050226 Sequence in context: A026656 A006491 A051721 this_sequence A119562 A166590 
               A085768
%Y A050226 Adjacent sequences: A050223 A050224 A050225 this_sequence A050227 A050228 
               A050229
%K A050226 nonn,nice
%O A050226 1,2
%A A050226 Labos E. (labos(AT)ana.sote.hu), Dec 20 1999
%E A050226 More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 21 2000. Further 
               terms from Naohiro Nomoto (6284968128(AT)geocities.co.jp), Aug 03 
               2001.
%E A050226 a(26)-a(30) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 
               21 2008