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 A155603 #19 Mar 10 2022 05:19:39
%S A155603 1,7,33,151,705,3367,16353,80311,397185,1972807,9824673,49005271,
%T A155603 244672065,1222297447,6108298593,30531927031,152630937345,
%U A155603 763068593287,3815084686113,19074648589591,95370918425025,476847618556327
%N A155603 a(n) = 5^n+3^n-1.
%H A155603 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-23,15).
%F A155603 G.f.: 1/(1-5*x)+1/(1-3*x)-1/(1-x).
%F A155603 E.g.f.: e^(5*x)+e^(3*x)-e^x.
%F A155603 a(n) = 8*a(n-1)-15*a(n-2)-8 with a(0)=1, a(1)=7. - _Vincenzo Librandi_, Jul 21 2010
%F A155603 a(n) = A074606(n)-1. - _R. J. Mathar_, Mar 10 2022
%t A155603 Table[5^n+3^n-1,{n,0,30}] (* or *) LinearRecurrence[{9,-23,15},{1,7,33},30] (* _Harvey P. Dale_, Oct 14 2020 *)
%o A155603 (PARI) a(n)=5^n+3^n-1 \\ _Charles R Greathouse IV_, Jun 11 2015
%Y A155603 Cf. A074501, A020515, A155588, A155590, A155592, A155593, A155594, A155596, A155597, A155598, A155599, A155600, A155601, A155602.
%K A155603 nonn,easy
%O A155603 0,2
%A A155603 _Mohammad K. Azarian_, Jan 25 2009