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 A072904 #13 Jun 24 2022 05:22:58 %S A072904 18,20,27,32,45,48,50,52,54,63,68,72,75,80,84,90,96,98,99,108,112,116, %T A072904 117,125,126,128,132,135,147,148,150,153,160,162,164,171,175,176,180, %U A072904 189,192,198,200,207,208,212,216,224,228,234,240,242,243,244,245,250 %N A072904 Nonsquares m such that the discriminant of the quadratic field Q(sqrt(m)) < m. %H A072904 Amiram Eldar, <a href="/A072904/b072904.txt">Table of n, a(n) for n = 1..10000</a> %F A072904 a(n) appears to be asymptotic to C*n with C = 3.4... . %t A072904 Select[Range[250], !IntegerQ@Sqrt[#] && NumberFieldDiscriminant[Sqrt[#]] < # &] (* _Amiram Eldar_, Jun 24 2022 *) %o A072904 (PARI) isok(m) = !issquare(m) && (quaddisc(m) < m); \\ _Michel Marcus_, Feb 18 2021 %Y A072904 Cf. A037449. %Y A072904 Intersection of A000037 and A072903. %K A072904 easy,nonn %O A072904 1,1 %A A072904 _Benoit Cloitre_, Aug 10 2002