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 A255043 #19 Jan 14 2023 12:41:25
%S A255043 2,22,202,1822,16402,147622,1328602,11957422,107616802,968551222,
%T A255043 8716961002,78452649022,706073841202,6354664570822,57191981137402,
%U A255043 514727830236622,4632550472129602,41692954249166422,375236588242497802,3377129294182480222
%N A255043 a(n) = (5*9^n - 1)/2.
%H A255043 G. C. Greubel, <a href="/A255043/b255043.txt">Table of n, a(n) for n = 0..1000</a>
%H A255043 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (10,-9).
%F A255043 G.f.: 2*(1+x)/((1-x)*(1-9*x)).
%F A255043 Recurrence: a(n) = 10*a(n-1) - 9*a(n-2), n>=2, a(0) = 2, a(1) = 22.
%F A255043 a(n) = 2*A138894(n).
%F A255043 E.g.f.: (5*exp(9*x) - exp(x))/2. - _G. C. Greubel_, Feb 07 2021
%t A255043 Table[(5*9^n - 1)/2, {n, 0, 19}]
%t A255043 LinearRecurrence[{10,-9},{2,22},20] (* _Harvey P. Dale_, Jun 15 2018 *)
%o A255043 (Sage) [(5*9^n -1)/2 for n in (0..20)] # _G. C. Greubel_, Feb 07 2021
%o A255043 (Magma) [(5*9^n -1)/2: n in [0..20]]; // _G. C. Greubel_, Feb 07 2021
%Y A255043 Cf. A096053, A138894, A191681, A198964, A198969.
%Y A255043 Row 2 of A255044.
%K A255043 nonn,easy
%O A255043 0,1
%A A255043 _L. Edson Jeffery_, Feb 13 2015