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 A175569 #4 Jun 19 2021 11:45:05
%S A175569 2,3,10,19,30,44,59,77,100,124,150,181,216,252,289,328,371,416,464,
%T A175569 515,567,620,675,739,807,879,962,1046,1131,1217,1312,1413,1522,1633,
%U A175569 1746,1861,1978,2101,2226,2355,2488,2623,2761,2902,3044,3189,3335,3484,3642
%N A175569 a(0)=2; for n>=0, a(n+1) = a(n) + x where x is the smallest positive number which is not equal to a(i) +/- a(k) for any i, k, 0<=k<=i<=n.
%C A175569 The same as A047699 except for a(0)=2.
%t A175569 a=2;s={a};X=Complement[Range[10^4],{0,a,2a}];
%t A175569 Do[b=a+X[[1]];X=Complement[X,s+b,b-s,{b,2b}];AppendTo[s,b];a=b,{100}];s
%Y A175569 Cf. A047699.
%K A175569 nonn
%O A175569 0,1
%A A175569 _Zak Seidov_, Jul 14 2010
%E A175569 Offset corrected. - _R. J. Mathar_, Jun 19 2021