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 A190898 #19 Jul 22 2025 12:06:41 %S A190898 3,7,11,17,29,43,53,71,83,107,127,157,173,199,229,257,293,337,379,401, %T A190898 457,499,541,577,631,683,733,787,857,911,967,1031,1091,1163,1229,1297, %U A190898 1373,1447,1553,1601,1697,1787,1867,1973,2029,2129,2213,2339,2411,2503,2617,2707,2819,2927,3041,3137,3251,3457,3491,3607 %N A190898 Least odd prime p>n^2 with (n/p) = 1, where ( / ) is the Legendre symbol. %C A190898 Conjecture: a(n)<(n+1)^2 for all n>0. (See also A185150.) %C A190898 This conjecture implies that a(1),a(2),a(3),... are pairwise distinct. %H A190898 Zhi-Wei Sun, <a href="/A190898/b190898.txt">Table of n, a(n) for n = 1..10000</a> %H A190898 Zhi-Wei Sun, <a href="http://arxiv.org/abs/1211.1588">Conjectures involving primes and quadratic forms</a>, arXiv:1211.1588. %e A190898 a(2)=7 since 7 is the first prime p>2^2 with (2/p) = 1. %t A190898 Do[Do[If[n^2+k>2&&PrimeQ[n^2+k]==True&&JacobiSymbol[n,n^2+k]==1,Print[n," ",n^2+k];Goto[aa]],{k,1,2n}]; %t A190898 Label[aa];Continue,{n,1,100}] %t A190898 js[n_]:=Module[{p=NextPrime[n^2]},While[JacobiSymbol[n,p]!=1,p= NextPrime[ p]];p]; Join[{3},Array[js,60,2]] (* _Harvey P. Dale_, Jan 29 2023 *) %Y A190898 Cf. A180150, A014085, A185636. %K A190898 nonn,nice %O A190898 1,1 %A A190898 _Zhi-Wei Sun_, Dec 29 2012