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 A138307 #2 Mar 30 2012 17:22:47 %S A138307 2,4,6,14,16,26,36,38,64,100,144,196,206,256,324,332,400,484,530,576, %T A138307 676,784,900,1024,1156,1296,1444,1600,1764,1936,2116,2304,2500,2704, %U A138307 2916,3136,3364,3600,3844,4096,4356,4624,4900,5184,5476,5776,6084,6400 %N A138307 Even numbers not representable as p+g, where p is a prime and g is a prime primitive root of p. %C A138307 This sequence appears to contain the squares of all even numbers (A016742) and a thin set of other numbers (A138318). %Y A138307 Cf. A138305 (prime primitive roots). %K A138307 nonn %O A138307 1,1 %A A138307 _T. D. Noe_, Mar 14 2008