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 A075122 #3 Mar 02 2015 16:08:48 %S A075122 1,2,3,4,6,12,17,18,19,20,21,22,23,24,29,31,32,33,34,73,94,96,102,103, %T A075122 104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120, %U A075122 121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137 %N A075122 a(n) = least positive integer > a(n-1) and not a(i)+2*a(j) for 1<=i<j<n. %Y A075122 Cf. A033627, A003278, A026471, A075123. %K A075122 nonn %O A075122 1,2 %A A075122 _Floor van Lamoen_, Sep 02 2002