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 A225946 #18 Aug 18 2015 04:54:34
%S A225946 2,3,17,24,30,40,44,84,87,99,130,182,260,288,442,448,635,650,672,675,
%T A225946 888,894,1211,1299,1368,1605,1616,1722,1748,1955,2034,2499,2541,3150,
%U A225946 3287,3782,4224,4400,4920,5073,5619,6723,7242,7310,8487,9228,10200,11055
%N A225946 Nonsquare k such that the minimal (in y) solution 0 < y < x of x^2 - k*y^2 = 1 has x-y square.
%C A225946 Numbers n such that A002350(n) - A002349(n) is a nonzero square. - _Charles R Greathouse IV_, Jun 06 2013
%H A225946 Ray Chandler, <a href="/A225946/b225946.txt">Table of n, a(n) for n = 1..192</a>
%e A225946 3^2 - 2*2^2 = 1 and 3 - 2 = 1 (square), so a(1) = 2;
%e A225946 2^2 - 3*1^2 = 1 and 2 - 1 = 1 (square), so a(2) = 3;
%e A225946 33^2 - 17*8^2 = 25 and 33 - 8 = 25 (square), so a(3) = 17.
%t A225946 qQ[n_] := IntegerQ@Sqrt@n; Select[Range[500], ! qQ[#] && qQ[(x - y) /. ToRules[Expand[ Reduce[x^2 - #*y^2 == 1 && x>0 && y>0, {x,y}, Integers] /. C[1] -> 1]]] &] (* _Giovanni Resta_, May 25 2013 *)
%o A225946 (PARI) is(n)=if(issquare(n),return(0));my(cf=contfrac(sqrt(n)),t,N,D);for(i=1,#cf-1,t=cf[i+1];forstep(j=i,1,-1,t=cf[j]+1/t);N=numerator(t);D=denominator(t);if(N^2-n*D^2==1,return(issquare(N-D)))); warning("Insufficient precision for "n) \\ _Charles R Greathouse IV_, Jun 06 2013
%Y A225946 Cf. A000037, A033313, A033317.
%K A225946 nonn
%O A225946 1,1
%A A225946 _Irina Gerasimova_, May 21 2013
%E A225946 a(15)-a(47) from _Giovanni Resta_, May 25 2013