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 A197120 #10 May 10 2025 02:30:40
%S A197120 5,13,20,29,45,52,53,61,80,85,109,116,117,125,149,157,173,180,181,208,
%T A197120 212,229,244,245,261,277,293,317,320,325,340,365,397,405,421,436,445,
%U A197120 461,464,468,477,493,500,509,533,541,549,565,596,605,613,628,629,637
%N A197120 Nonsquare positive integers n such that the fundamental unit of quadratic field Q(sqrt(d))has norm -1 and minimum one from two parts of fundamental unit are not integer.
%C A197120 Numbers that occur in A172000 and not in A197115.
%t A197120 cr = {}; Do[ If[IntegerQ[Sqrt[n]], , kk = NumberFieldFundamentalUnits[Sqrt[n]]; d1 = kk[[1]][[2]][[1]]; d2 = kk[[1]][[1]] kk[[1]][[2]][[2]]; d3 = Expand[(d1 + d2) (d1 - d2)]; If[d3 == -1, k1 = Max[Denominator[d1], Denominator[d2]]; If[k1 == 1, , AppendTo[cr, n]]]], {n, 2, 2000}]; cr
%Y A197120 Cf. A087643, A172000, A194366, A197115.
%K A197120 nonn
%O A197120 1,1
%A A197120 _Artur Jasinski_, Oct 10 2011