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 A120845 #28 May 07 2023 05:38:23
%S A120845 2,10,23,50,117,300,823,2350,6857,20240,60123,179250,535597,1602580,
%T A120845 4799423,14381750,43112337,129271320,387682723,1162785850,3487833077,
%U A120845 10462450460,31385254023,94151567550,282446313817,847322164000,2541932937323,7625731702850,22877060890557
%N A120845 a(n) = 2^n + 3^n + 5*n.
%H A120845 Vincenzo Librandi, <a href="/A120845/b120845.txt">Table of n, a(n) for n = 0..1000</a>
%H A120845 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (7,-17,17,-6).
%F A120845 G.f.: (2-4*x-13*x^2+25*x^3)/((1-2*x)*(1-3*x)*(1-x)^2). - _Bruno Berselli_, Sep 01 2011
%F A120845 a(n) = 7*a(n-1)-17*a(n-2)+17*a(n-3)-6*a(n-4). - _Vincenzo Librandi_, Feb 26 2013
%F A120845 E.g.f.: exp(x)*(exp(x) + exp(2*x) + 5*x). - _Stefano Spezia_, May 06 2023
%t A120845 CoefficientList[Series[(2 - 4 x - 13 x^2 + 25 x^3)/((1-2 x) (1-3 x) (1-x)^2), {x, 0, 30}], x] (* _Vincenzo Librandi_, Feb 26 2013 *)
%t A120845 LinearRecurrence[{7,-17,17,-6},{2,10,23,50},30] (* _Harvey P. Dale_, Apr 28 2016 *)
%o A120845 (Magma) I:=[2, 10, 23, 50]; [n le 4 select I[n] else 7*Self(n-1)-17*Self(n-2)+17*Self(n-3)-6*Self(n-4): n in [1..30]]; // _Vincenzo Librandi_, Feb 26 2013
%Y A120845 Cf. A001047, A007689, A194455.
%K A120845 nonn,easy
%O A120845 0,1
%A A120845 _Mohammad K. Azarian_, Aug 18 2006
%E A120845 Edited by _Ray Chandler_, Sep 06 2006