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 A031428 #22 Jul 12 2021 02:03:19 %S A031428 5,18,39,68,105,150,174,203,264,333,370,410,495,588,689,793,798,855, %T A031428 915,1040,1105,1173,1313,1314,1378,1387,1462,1463,1620,1785,1958,2138, %U A031428 2139,2222,2232,2328,2525,2730,2834,2943,3164,3393,3630,3741 %N A031428 Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 4. %H A031428 Charles R Greathouse IV, <a href="/A031428/b031428.txt">Table of n, a(n) for n = 1..10000</a> (first 700 terms from Vincenzo Librandi) %t A031428 Select[Range[4000], !IntegerQ[Sqrt[#]] && Min[ContinuedFraction[Sqrt[#]][[2]]] == 4&] (* _Vincenzo Librandi_, Feb 06 2012 *) %Y A031428 Different from A007742. %Y A031428 Cf. A031424. %K A031428 nonn %O A031428 1,1 %A A031428 _David W. Wilson_