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 A022939 #7 Apr 04 2016 18:52:31
%S A022939 1,2,4,7,10,15,19,26,31,39,45,55,62,73,82,94,104,117,128,142,155,170,
%T A022939 184,200,216,233,250,268,286,305,324,345,365,387,408,431,454,478,502,
%U A022939 527,552,578,604,631,658,687,715,745,774,805,835,868,899
%N A022939 Unique increasing sequence satisfying a(n) = a(n-2) + c(n-2); where c( ) is complement of a( ).
%H A022939 Ivan Neretin, <a href="/A022939/b022939.txt">Table of n, a(n) for n = 1..10000</a>
%t A022939 Fold[Append[#1, #1[[#2]] + Complement[Range[Max@#1 + 1], #1][[#2]]] &, {1, 2}, Range[50]] (* _Ivan Neretin_, Apr 04 2016 *)
%Y A022939 Cf. A005228 and references therein.
%K A022939 nonn
%O A022939 1,2
%A A022939 _Clark Kimberling_