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 A099974 #16 Aug 02 2025 18:14:10
%S A099974 1,5,13,141,653,1677,3725,20109,544397,2641549,6835853,15224461,
%T A099974 32001677,65556109,132664973,266882701,803753613,1877495437,
%U A099974 4024979085,8319946381,16909880973,51269619341,601025433229,1700537061005
%N A099974 Write log(2) as a binary fraction; read this from left to right and whenever a 1 appears, note the integer formed by reading leftwards from that 1.
%e A099974 log(2) = 0.69314718055994530941723212145817656807550013436025525412... = 0.1011000101110010000101111111011111010001110011110111100110101011110010011110... in binary.
%t A099974 d = 100; l = First[RealDigits[N[Log[2], d], 2]]; Do[m = Take[l, n]; k = Length[m]; If[m[[k]] == 1, Print[FromDigits[Reverse[m], 2]]], {n, 1, d}] (* _Ryan Propper_, Aug 17 2005 *)
%t A099974 Module[{nn=50,l2},l2=RealDigits[Log[2],2,nn][[1]];Table[FromDigits[ Reverse[ Take[ l2,n]],2],{n,nn}]]//Union (* _Harvey P. Dale_, Mar 29 2016 *)
%Y A099974 Cf. A002162, A099969, A099970, A099971, A099972, A099973.
%K A099974 nonn,easy
%O A099974 0,2
%A A099974 _N. J. A. Sloane_, Nov 13 2004, based on correspondence from _Artur Jasinski_, Mar 25 2003
%E A099974 More terms from _Ryan Propper_, Aug 17 2005