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 A034018 #6 Jul 08 2025 20:01:50 %S A034018 4,9,12,16,25,27,28,36,48,52,63,64,75,76,81,84,100,108,112,117,121, %T A034018 124,144,148,156,171,172,175,189,192,196,208,225,228,243,244,252,256, %U A034018 268,279,289,292,300,304,316,324,325,333,336,351,363,364,372,387,388,400 %N A034018 Numbers that are represented by x^2+xy+y^2 but not primitively. %Y A034018 Cf. A034017. %K A034018 nonn %O A034018 1,1 %A A034018 _N. J. A. Sloane_ %E A034018 Extended by _Ray Chandler_, Jan 29 2009