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 A115012 #4 Mar 30 2012 16:50:23
%S A115012 1,3,6,10,10,16,23,31,40,40,51,63,76,90,90,106,123,141,160,160,181,
%T A115012 203,226,250,250,276,303,331,360,360,391,423,456,490,490,526,563,601,
%U A115012 640,640,681,723,766,810,810,856,903,951,1000,1000,1051,1103,1156,1210,1210,1266
%N A115012 Sum_{i=1..n, gcd(5,i)=1} i.
%Y A115012 Replacing 5 in the definition by 2, 3, 4, 5, 6, 7, 8, 9 gives respectively A008794, A068626, A008794, this sequence, A115014, A115015, A008794, A068626.
%K A115012 nonn
%O A115012 1,2
%A A115012 _N. J. A. Sloane_, Feb 24 2006