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 A065126 #15 Dec 24 2014 14:43:27
%S A065126 11,19,22,29,31,33,38,41,44,55,57,58,59,61,62,66,71,76,77,79,82,87,88,
%T A065126 89,93,95,99,101,109,110,114,116,118,122,123,124,131,132,133,139,142,
%U A065126 143,145,149,151,152,154,155,158,164,165,171,174,176,177,178,179,181
%N A065126 Numbers n for which sigma_2(n^2) == 3 (mod 10).
%C A065126 It appears that sigma_2( m^2 ) = 3 (mod 10) iff m is divisible by a prime p = 1 or 9 (mod 10), else sigma_2( m^2 ) = 1 (mod 10). - _M. F. Hasler_, May 14 2008
%C A065126 This seems also to be numbers whose square is expressible in only one way as x^2 + 3xy + y^2, with 0 < x < y. - _Colin Barker_, Dec 24 2014
%H A065126 M. F. Hasler, <a href="/A065126/b065126.txt">Table of n, a(n) for n=1..7747</a>.
%F A065126 Mod[DivisorSigma[2, n^2], 10]=3.
%e A065126 n=29: sigma[2,29^2] = sigma[2,841] = 708123 = 10.70812+3; among the numbers all residues modulo 8 occur.
%t A065126 Select[Range[200],Mod[DivisorSigma[2,#^2],10]==3&] (* _Harvey P. Dale_, Oct 21 2011 *)
%o A065126 (PARI) c=0; for( n=1,10^5,sigma(n^2,2)%5==3 & write("b065126.txt",c++" "n)) \\ _M. F. Hasler_, May 14 2008
%Y A065126 Cf. A000290, A001157, A057660, A065803.
%K A065126 easy,nonn
%O A065126 1,1
%A A065126 _Labos Elemer_, Nov 21 2001
%E A065126 More terms and better description from _M. F. Hasler_, May 14 2008