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 A145641 #24 Aug 08 2024 16:18:50
%S A145641 5,51,455,3855,31775,258111,2080895,16711935,133956095,1072694271,
%T A145641 8585742335,68702703615,549688713215,4397778092031,35183298379775,
%U A145641 281470681808895,2251782633947135,18014329790267391,144114913198473215,1152920405096267775,9223367638810361855
%N A145641 Numbers whose binary representation is the concatenation of n 1's, n 0's and n 1's.
%C A145641 Numbers whose binary representation are the members of A138721.
%H A145641 Paolo Xausa, <a href="/A145641/b145641.txt">Table of n, a(n) for n = 1..1000</a>
%H A145641 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (15,-70,120,-64).
%F A145641 G.f.: x*(40*x^2-24*x+5)/((x-1)*(2*x-1)*(4*x-1)*(8*x-1)). - _Colin Barker_, Nov 04 2012
%F A145641 a(n) = (2^n-1)*(2^(2*n)+1) = 8^n - 4^n + 2^n - 1. - _Alois P. Heinz_, Nov 04 2012
%p A145641 a:= n-> 8^n-4^n+2^n-1:
%p A145641 seq(a(n), n=1..30); # _Alois P. Heinz_, Nov 04 2012
%t A145641 Table[8^n - 4^n + 2^n - 1, {n, 25}] (* _Paolo Xausa_, Aug 08 2024 *)
%Y A145641 Cf. A138721.
%K A145641 easy,nonn,base
%O A145641 1,1
%A A145641 _Omar E. Pol_, Oct 14 2008
%E A145641 More terms from _Colin Barker_, Nov 04 2012