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 A330220 #9 Jul 23 2025 16:01:20
%S A330220 0,1,2,3,4,5,7,8,9,10,15,16,17,18,21,31,32,33,34,36,42,63,64,65,66,68,
%T A330220 73,85,127,128,129,130,132,136,146,170,255,256,257,258,260,264,273,
%U A330220 292,341,511,512,513,514,516,520,528,546,585,682,1023,1024,1025,1026
%N A330220 Numbers whose representation in base 2^w contains only the digit 2^k for some w and k such that 0 <= k < w.
%C A330220 This is a subsequence of A295235.
%C A330220 For any k > 0, there are k nonzero terms with k binary digits.
%C A330220 Odd terms are A064896.
%e A330220 The representation of 546 in base 2^4 is "222", so 546 belongs to the sequence.
%o A330220 (PARI) is(n) = { for (w=1, max(1, #binary(n)), my (d=if (n, digits(n,2^w), [0])); if (#Set(d)==1 && hammingweight(d[1])<=1, return (1))); return (0) }
%Y A330220 Cf. A064896, A295235.
%K A330220 nonn,base
%O A330220 1,3
%A A330220 _Rémy Sigrist_, Dec 06 2019