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 A043725 #16 Oct 04 2023 23:44:59 %S A043725 1,3,7,15,21,31,37,41,43,45,53,63,69,73,75,77,81,83,87,89,91,93,101, %T A043725 105,107,109,117,127,133,137,139,141,145,147,151,153,155,157,161,163, %U A043725 167,175,177,179,183,185,187,189,197,201,203,205 %N A043725 Numbers whose number of runs in the base-2 representation is congruent to 1 mod 4. %H A043725 Harvey P. Dale, <a href="/A043725/b043725.txt">Table of n, a(n) for n = 1..1000</a> %H A043725 Paul Barry, <a href="https://arxiv.org/abs/2107.00442">Conjectures and results on some generalized Rueppel sequences</a>, arXiv:2107.00442 [math.CO], 2021. %t A043725 Select[Range[250],Mod[Length[Split[IntegerDigits[#,2]]],4]==1&] (* _Harvey P. Dale_, Dec 10 2018 *) %K A043725 nonn,base %O A043725 1,2 %A A043725 _Clark Kimberling_