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 A196657 #22 Sep 08 2022 08:45:59
%S A196657 127,253,505,1009,2017,4033,8065,16129,32257,64513,129025,258049,
%T A196657 516097,1032193,2064385,4128769,8257537,16515073,33030145,66060289,
%U A196657 132120577,264241153,528482305,1056964609,2113929217,4227858433,8455716865,16911433729,33822867457
%N A196657 63*2^(n+1) + 1.
%C A196657 Binary numbers of form 111111(n)1 where n is the index and number of 0's.
%H A196657 Vincenzo Librandi, <a href="/A196657/b196657.txt">Table of n, a(n) for n = 0..1000</a>
%H A196657 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2).
%e A196657 First few terms in binary are 1111111, 11111101, 111111001, 1111110001, 11111100001.
%t A196657 LinearRecurrence[{3,-2},{127,253},50] (* _Vincenzo Librandi_, Nov 25 2011 *)
%o A196657 (Magma) [63*2^(n+1) + 1: n in [0..100]];
%o A196657 (PARI) a(n)=126<<n+1 \\ _Charles R Greathouse IV_, Oct 06 2011
%K A196657 nonn,easy
%O A196657 0,1
%A A196657 _Brad Clardy_, Oct 04 2011