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 A298879 #17 Sep 08 2022 08:46:20
%S A298879 0,3,6,12,13,15,21,24,26,27,30,37,42,45,47,48,52,53,54,57,60,61,63,69,
%T A298879 73,74,81,83,84,90,93,94,96,99,104,105,106,107,108,109,111,114,115,
%U A298879 119,120,122,123,126,133,137,138,141,146,148,151,155,159
%N A298879 Numbers whose square is not odious.
%C A298879 Complement of A235331.
%C A298879 From _Robert Israel_, Feb 02 2018: (Start)
%C A298879 2*n is in the sequence if and only if n is in the sequence.
%C A298879 2*n+1 is in the sequence if and only if n*(n+1) is odious. (End)
%p A298879 select(t -> convert(convert(t^2,base,2),`+`)::even, [$0..200]); # _Robert Israel_, Feb 02 2018
%t A298879 Join[{0}, Select[Range[200], !OddQ[DigitCount[#^2, 2][[1]]] &]]
%o A298879 (Magma) [n: n in [0..200] | IsEven(&+Intseq(n^2, 2))];
%o A298879 (PARI) isok(n) = (hammingweight(n^2) % 2) != 1; \\ _Michel Marcus_, Jan 31 2018
%Y A298879 Cf. A235001, A235331.
%K A298879 nonn,easy
%O A298879 1,2
%A A298879 _Vincenzo Librandi_, Jan 31 2018