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 A155594 #17 Mar 10 2022 05:31:17
%S A155594 1,11,103,1007,10015,100031,1000063,10000127,100000255,1000000511,
%T A155594 10000001023,100000002047,1000000004095,10000000008191,
%U A155594 100000000016383,1000000000032767,10000000000065535,100000000000131071
%N A155594 10^n+2^n-1.
%H A155594 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (13,-32,20).
%F A155594 G.f.: 1/(1-10*x)+1/(1-2*x)-1/(1-x). E.g.f.: e^(10*x)+e^(2*x)-e^x.
%F A155594 a(n)=12*a(n-1)-20*a(n-2)-9 with a(0)=1, a(1)=11 - _Vincenzo Librandi_, Jul 21 2010
%F A155594 a(0)=1, a(1)=11, a(2)=103, a(n)=13*a(n-1)-32*a(n-2)+20*a(n-3). - _Harvey P. Dale_, Mar 07 2015
%F A155594 a(n) = A050621(n+1)-1. - _R. J. Mathar_, Mar 10 2022
%t A155594 LinearRecurrence[{13,-32,20},{1,11,103},20] (* _Harvey P. Dale_, Mar 07 2015 *)
%o A155594 (PARI) a(n)=10^n+2^n-1^n \\ _Charles R Greathouse IV_, Jun 11 2015
%Y A155594 Cf. A074501, A074600, A005057, A005056, A099393, A155588, A155590, A155592, A155593.
%K A155594 nonn,easy
%O A155594 0,2
%A A155594 _Mohammad K. Azarian_, Jan 24 2009