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 A227697 #11 Nov 26 2013 04:30:37 %S A227697 2,4,6,7,9,12,16,18,21,22,24,27,30,36,37,39,42,46,48,51,57,60,66,67, %T A227697 69,72,81,87,90,102,106,108,111,120,121,123,126,132,135,141,150,156, %U A227697 165,171,172,174,177,186,192,207,210 %N A227697 Numbers of the form ((p^2 + q^2)/2 - 1)/4, where p and q are odd primes. %C A227697 a(n) mod 3 = 0 if neither prime = 3. %C A227697 a(n) mod 3 = 1 if one prime = 3. %C A227697 a(1) mod 3 = 2 (where both primes = 3). %F A227697 a(n) = (A143850(n)-1)/4. %K A227697 nonn %O A227697 1,1 %A A227697 _Richard R. Forberg_, Sep 22 2013