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 A011631 #8 Jul 08 2025 02:31:45 %S A011631 0,1,-1,1,1,1,-1,1,-1,1,-1,-1,1,1,-1,1,1,1,-1,-1,1,1,1,1,-1,1,-1,1,1, %T A011631 -1,-1,1,-1,-1,-1,1,1,-1,1,1,-1,1,-1,-1,-1,1,-1,-1,1,1,-1,1,1,-1,-1, %U A011631 -1,-1,-1,1,-1,1,-1,-1,1,1,1,1,1,1,1,-1,-1,-1,1,1,1,-1,-1,-1,1,1 %N A011631 Legendre symbol (n,251). %D A011631 G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 68. %K A011631 sign,mult %O A011631 0,1 %A A011631 _N. J. A. Sloane_