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 A155621 #13 Jul 22 2025 06:19:06
%S A155621 1,13,115,1063,10255,101023,1004095,10016383,100065535,1000262143,
%T A155621 10001048575,100004194303,1000016777215,10000067108863,
%U A155621 100000268435455,1000001073741823,10000004294967295,100000017179869183
%N A155621 10^n+4^n-1^n.
%H A155621 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (15,-54,40).
%F A155621 G.f.: 1/(1-10*x)+1/(1-4*x)-1/(1-x). E.g.f.: e^(10*x)+e^(4*x)-e^x.
%F A155621 a(n)=14*a(n-1)-40*a(n-2)-27 with a(0)=1, a(1)=13 [From _Vincenzo Librandi_, Jul 21 2010]
%t A155621 LinearRecurrence[{15,-54,40},{1,13,115},20] (* _Harvey P. Dale_, Oct 24 2016 *)
%Y A155621 A155588, A155599, A155607, A155608, A155609, A155610, A155611, A155612, A155613, A155614, A155615, A155616, A155617, A155618, A155619, A155620
%K A155621 nonn
%O A155621 0,2
%A A155621 _Mohammad K. Azarian_, Jan 27 2009