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 A248401 #12 Oct 13 2019 04:17:55 %S A248401 43,131,163,417,491,537,571,619,849,913,923,1019,1187,1203,1579,1641, %T A248401 1707,1747,1779,1835,1843,1907,2003,2051,2123,2203,2227,2235,2315, %U A248401 2537,2563,2649,2747,2787,2913,2931,3083,3107,3307,3345,3363,3561,3587,3611,3651,3659 %N A248401 Noncongruent squarefree numbers n with A248394(n)/d(n) = 3, where d(n) = A000005(n). %H A248401 J. B. Tunnell, <a href="http://dx.doi.org/10.1007/BF01389327">A classical Diophantine problem and modular forms of weight 3/2</a>, Invent. Math., 72 (1983), 323-334. %Y A248401 Cf. A000005, A003273, A165564, A248394, A248395, A248397-A248407. %K A248401 nonn %O A248401 1,1 %A A248401 _N. J. A. Sloane_, Oct 20 2014 %E A248401 More terms from _Amiram Eldar_, Oct 13 2019