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 A249052 #10 Jun 26 2022 16:18:02 %S A249052 205,221,305,377,505,545,689,725,745,793,905,1205,1345,1405,1469,1513, %T A249052 1517,1537,1717,1885,1945,1961,2005,2041,2045,2105,2225,2245,2329, %U A249052 2353,2525,2533,2669,2701,2845,2993,3005,3205,3305,3497,3505,3737,3757,3805,3893,3965,4069,4105,4145,4205,4321,4369 %N A249052 Odd numbers n without prime factors of the form 4k+3 such that x^2-n*y^2=-1 has no solutions. %C A249052 A positive odd integer n is in this sequence iff its squarefree core A007913(n) belongs to A031398. - _Max Alekseyev_, Jun 26 2022 %Y A249052 Odd terms of A172001. %Y A249052 Cf. A031398, A031399, A137351. %K A249052 nonn %O A249052 1,1 %A A249052 _Joerg Arndt_, Apr 09 2008