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 A155598 #25 Mar 10 2022 05:24:02
%S A155598 1,6,46,336,2386,16776,117586,823416,5764546,40353096,282474226,
%T A155598 1977324696,13841283106,96889002216,678223056466,4747561477176,
%U A155598 33232930504066,232630513856136,1628413597648306,11398895184848856
%N A155598 a(n) = 7^n-2^n+1.
%H A155598 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (10,-23,14).
%F A155598 G.f.: 1/(1-7*x)-1/(1-2*x)+1/(1-x). E.g.f.: e^(7*x)-e^(2*x)+e^x.
%F A155598 a(n) = 9*a(n-1)-14*a(n-2)+6 with a(0)=1, a(1)=6 - _Vincenzo Librandi_, Jul 21 2010
%F A155598 a(0)=1, a(1)=6, a(2)=46, a(n) = 10*a(n-1)-23*a(n-2)+14*a(n-3). - _Harvey P. Dale_, Feb 28 2013
%F A155598 a(n) = A190540(n)+1. - _R. J. Mathar_, Mar 10 2022
%t A155598 Table[7^n-2^n+1,{n,0,20}] (* or *) LinearRecurrence[{10,-23,14},{1,6,46},20] (* _Harvey P. Dale_, Feb 28 2013 *)
%o A155598 (PARI) a(n)=7^n-2^n+1 \\ _Charles R Greathouse IV_, Sep 24 2015
%Y A155598 Cf. A074501, A020515, A155588, A155590, A155592, A155593, A155594, A155596, A155597.
%K A155598 nonn,easy
%O A155598 0,2
%A A155598 _Mohammad K. Azarian_, Jan 25 2009