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 A206523 #6 Mar 30 2012 16:52:09 %S A206523 4,9,11,19,21,26,31,33,38,44,46,48,51,61,68,70,73,75,85,91,93,97,98, %T A206523 108,110,120,123,125,130,133,140,152,157,162,164,165,169,179,189,191, %U A206523 203,204,205,210,212,220,228,232,245,251,261,263,268,269,278,283,290,292,303,306,308,313,323,324,327,335,348,350,363,372,382,389,391,395,396,406,417,418,419,421 %N A206523 The pairwise sums of the terms of A004210. %Y A206523 Cf. A004210, A206522, A206524. %K A206523 nonn %O A206523 1,1 %A A206523 _N. J. A. Sloane_, Feb 08 2012