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 A223024 #45 Apr 25 2024 06:42:07 %S A223024 0,4,7,10,11,13,15,16,19,20,22,28,29,30,34,36,41,43,46,48,49,50,53,54, %T A223024 56,62,63,65,66,67,68,69,80,82,83,84,85,86,87,88,89,90,91,92,93,94,95, %U A223024 97,98,100,101,103,107,108,110,111,113,114,115,117,118,119,120 %N A223024 Numbers k such that 3^k is odious (A000069). %H A223024 Peter J. C. Moses, <a href="/A223024/b223024.txt">Table of n, a(n) for n = 1..10000</a> %p A223024 select(t -> convert(convert(3^t,base,2),`+`)::odd, [$0..200]); # _Robert Israel_, Oct 10 2016 %t A223024 Select[Range[0,200], OddQ[DigitCount[3^#,2][[1]]]&] (* _Peter J. C. Moses_, Mar 30 2013 *) %o A223024 (PARI) isok(n) = (hammingweight(3^n) % 2) == 1; \\ _Michel Marcus_, Oct 11 2016 %Y A223024 Cf. A000069, A001969, A000244, A237545. %Y A223024 Complement of A371970. %K A223024 nonn,base %O A223024 1,2 %A A223024 _Vladimir Shevelev_, Mar 29 2013