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 A084244 #19 Mar 20 2023 21:07:05
%S A084244 1,5,-15,45,-135,405,-1215,3645,-10935,32805,-98415,295245,-885735,
%T A084244 2657205,-7971615,23914845,-71744535,215233605,-645700815,1937102445,
%U A084244 -5811307335,17433922005,-52301766015,156905298045,-470715894135,1412147682405,-4236443047215
%N A084244 a(0)=1, a(1)=5, a(n) = -3*a(n-1), n>1.
%C A084244 Binomial transform is A083581.
%H A084244 Winston de Greef, <a href="/A084244/b084244.txt">Table of n, a(n) for n = 0..2081</a>
%H A084244 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (-3).
%F A084244 a(n) = 8*0^n/3 - 5*(-3)^n/3.
%F A084244 G.f.: (1 + 8*x)/(1 + 3*x).
%F A084244 E.g.f.: (8 - 5*exp(-3*x))/3.
%t A084244 Join[{1},NestList[-3#&,5,30]] (* _Harvey P. Dale_, Jan 29 2013 *)
%o A084244 (PARI) a(n)=8*0^n/3 - 5*(-3)^n/3 \\ _Winston de Greef_, Mar 19 2023
%Y A084244 Cf. A083581.
%K A084244 easy,sign
%O A084244 0,2
%A A084244 _Paul Barry_, May 23 2003