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 A220089 #16 Nov 11 2023 11:00:35
%S A220089 -242,-241,-239,-235,-227,-211,-179,-115,13,269,781,1805,3853,7949,
%T A220089 16141,32525,65293,130829,261901,524045,1048333,2096909,4194061,
%U A220089 8388365,16776973,33554189,67108621,134217485,268435213,536870669,1073741581,2147483405,4294967053
%N A220089 a(n) = 2^n - 243.
%H A220089 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (3,-2).
%F A220089 From _Chai Wah Wu_, Jan 17 2020: (Start)
%F A220089 a(n) = 3*a(n-1) - 2*a(n-2) for n > 1.
%F A220089 G.f.: (485*x - 242)/((x - 1)*(2*x - 1)). (End)
%F A220089 From _Elmo R. Oliveira_, Nov 11 2023: (Start)
%F A220089 a(n) = 2*a(n-1) + 243 with a(0) = -242.
%F A220089 E.g.f.: exp(2*x) - 243*exp(x). (End)
%t A220089 Table[2^n - 243, {n, 0, 40}] (* _T. D. Noe_, Dec 04 2012 *)
%Y A220089 Cf. A000225, A036563, A185346, A220087, A220088.
%K A220089 sign
%O A220089 0,1
%A A220089 _Andreas Rieber_, Dec 04 2012