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 A253408 #25 Feb 19 2015 15:25:17 %S A253408 -1,1,7,17,23,31,41,47,49,71,73,79,89,97,103,113,119,127,137,151,161, %T A253408 167,191,193,199,217,223,233,239,241,257,263,271,281,287,289,311,313, %U A253408 329,337,343,353,359,367,383,391,401,409,431,433,439,449,457,463,479,487 %N A253408 Values of difference z-y that solve equation x^2 + y^2 = z^2 + 2. %C A253408 All values are congruent to +-1 (mod 8). %F A253408 a(n)^2 mod 8 = 1. %F A253408 a(n) = A058529(n-1), n>1. %e A253408 a(3)=7 because 25^2 + 41^2 = 48^2 + 2 and 48 - 41 = 7. %Y A253408 Cf. A058529. %K A253408 sign %O A253408 1,3 %A A253408 _Carmine Suriano_, Jan 05 2015