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 A034019 #7 Jul 08 2025 20:01:57 %S A034019 4,9,12,16,25,27,28,36,48,49,52,63,64,75,76,81,84,100,108,112,117,121, %T A034019 124,144,147,148,156,169,171,172,175,189,192,196,208,225,228,243,244, %U A034019 252,256,268,279,289,292,300,304,316,324,325,333,336,343 %N A034019 Numbers that are imprimitively (and possibly also primitively) represented by x^2+xy+y^2. %H A034019 Charles R Greathouse IV, <a href="/A034019/b034019.txt">Table of n, a(n) for n = 1..10000</a> %o A034019 (PARI) is(n)=my(f=factor(n),t); for(i=1, #f[, 1], if(f[i, 1]%3<2 && f[i,2]>1, t=1); if(f[i,1]%3==2, if(f[i,2]%2, return(0), t=1))); t \\ _Charles R Greathouse IV_, Nov 04 2015 %Y A034019 Cf. A045897, A034018, A003136. %K A034019 nonn %O A034019 1,1 %A A034019 _N. J. A. Sloane_