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 A352779 #37 Dec 18 2023 19:33:32
%S A352779 1,-3,9,-27,81,-243,729,-2187,6561,-19683,59049,-177147,531441,
%T A352779 -1594323,4782969,-14348907,43046721,-129140163,387420489,-1162261467,
%U A352779 3486784401,-10460353203,31381059609,-94143178827,282429536481,-847288609443,2541865828329,-7625597484987
%N A352779 Powers of -3: a(n) = (-3)^n.
%H A352779 Winston de Greef, <a href="/A352779/b352779.txt">Table of n, a(n) for n = 0..2082</a>
%H A352779 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (-3).
%F A352779 a(0) = 1; a(n) = -3*a(n-1), n >= 1.
%F A352779 G.f.: 1/(1+3*x).
%F A352779 a(n) = (-1)^n*A000244(n).
%F A352779 E.g.f.: 1/exp(3*x). - _Elmo R. Oliveira_, Dec 17 2023
%t A352779 LinearRecurrence[{-3}, {1}, 28]
%t A352779 CoefficientList[Series[1/(1+3*x), {x,0,27}], x]
%t A352779 Table[(-3)^n, {n,0,27}]
%o A352779 (PARI) a(n)=(-3)^n \\ _Winston de Greef_, Mar 19 2023
%Y A352779 Cf. A000244, A033999, A141413.
%K A352779 sign,easy
%O A352779 0,2
%A A352779 _L. Edson Jeffery_, Apr 04 2022