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 A011583 #25 Jul 08 2025 02:27:16
%S A011583 0,1,-1,1,1,-1,-1,-1,-1,1,1,-1,1,0,1,-1,1,1,-1,-1,-1,-1,1,1,-1,1,0,1,
%T A011583 -1,1,1,-1,-1,-1,-1,1,1,-1,1,0,1,-1,1,1,-1,-1,-1,-1,1,1,-1,1,0,1,-1,1,
%U A011583 1,-1,-1,-1,-1,1,1,-1,1,0,1,-1,1,1,-1,-1,-1,-1,1,1,-1,1,0,1,-1
%N A011583 Legendre symbol (n,13).
%C A011583 Since 13 is an odd prime, this is the same as the Jacobi symbol (n,13). - _Robert Israel_, Jun 29 2017
%D A011583 G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers. 3rd ed., Oxford Univ. Press, 1954, p. 68.
%H A011583 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1).
%F A011583 G.f.: (x+x^3+2*x^4+x^5-x^7-2*x^8-x^9-x^11) / (1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10+x^11+x^12). - _Robert Israel_, Jun 29 2017
%p A011583 seq(numtheory:-legendre(n,13),n=0..80); # _Robert Israel_, Jun 29 2017
%t A011583 Table[JacobiSymbol[n, 13], {n, 0, 80}] (* _Jean-François Alcover_, May 17 2017 *)
%o A011583 (PARI) A011583(n) = kronecker(n,13) ;
%o A011583 for(n=0,20,print1(A011583(n)",") ); /* _R. J. Mathar_, Feb 25 2012 */
%K A011583 sign,mult,easy
%O A011583 0,1
%A A011583 _N. J. A. Sloane_