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 A178671 #34 Aug 23 2024 13:40:38
%S A178671 -4,0,20,120,620,3120,15620,78120,390620,1953120,9765620,48828120,
%T A178671 244140620,1220703120,6103515620,30517578120,152587890620,
%U A178671 762939453120,3814697265620,19073486328120,95367431640620,476837158203120,2384185791015620,11920928955078120
%N A178671 a(n) = 5^n - 5.
%H A178671 Vincenzo Librandi, <a href="/A178671/b178671.txt">Table of n, a(n) for n = 0..1000</a>
%H A178671 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,-5).
%F A178671 a(n) = 5*a(n-1) + 20 with a(0) = -4.
%F A178671 From _R. J. Mathar_, Jan 03 2011: (Start)
%F A178671 G.f.: 4*(-1+6*x)/((1-5*x)*(1-x)).
%F A178671 a(n) = 4*A104891(n-1), n > 0. (End)
%F A178671 a(n) = 6*a(n-1) - 5*a(n-2) for n > 1. - _Vincenzo Librandi_, Jan 25 2013
%F A178671 E.g.f.: exp(5*x) - 5*exp(x). - _G. C. Greubel_, Jan 28 2019
%e A178671 a(n) = A178676(n)-10 = A242329(n)-9 = A242328(n)-7 = A034474(n)-6 = A000351(n)-5. - _Elmo R. Oliveira_, Dec 06 2023
%t A178671 5^Range[0,30]-5 (* _Vladimir Joseph Stephan Orlovsky_, Feb 20 2011 *)
%t A178671 LinearRecurrence[{6,-5},{-4,0},30] (* _Harvey P. Dale_, Aug 23 2024 *)
%o A178671 (Magma) [5^n-5: n in [0..25]];
%o A178671 (PARI) vector(30, n, n--; 5^n-5) \\ _G. C. Greubel_, Jan 28 2019
%o A178671 (Sage) [5^n-5 for n in range(30)] # _G. C. Greubel_, Jan 28 2019
%o A178671 (GAP) List([0..30], n -> 5^n-5); # _G. C. Greubel_, Jan 28 2019
%Y A178671 Cf. A000351, A034474, A178676, A242328, A242329.
%K A178671 sign,easy
%O A178671 0,1
%A A178671 _Vincenzo Librandi_, Dec 25 2010