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 A016185 #35 Nov 29 2024 17:31:19
%S A016185 0,1,17,217,2465,26281,269297,2685817,26269505,253202761,2413042577,
%T A016185 22791125017,213710059745,1992110014441,18478745943857,
%U A016185 170706760005817,1571545212141185,14425381885981321,132080236787517137,1206736529597136217,11004743954450081825
%N A016185 a(n) = 9^n - 8^n.
%C A016185 a(n) is also the number of n-digit numbers whose smallest decimal digit is 1. - _Stefano Spezia_, Nov 15 2023
%H A016185 G. C. Greubel, <a href="/A016185/b016185.txt">Table of n, a(n) for n = 0..1000</a>
%H A016185 John Elias, <a href="/A016185/a016185.png">Illustration of initial terms: Sierpinski Carpet</a>
%H A016185 Wikipedia, <a href="https://en.wikipedia.org/wiki/Sierpi%C5%84ski_carpet">Sierpinski carpet</a>
%H A016185 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (17,-72).
%F A016185 G.f.: x/((1-8*x)*(1-9*x)).
%F A016185 E.g.f.: e^(9*x) - e^(8*x). - _Mohammad K. Azarian_, Jan 14 2009
%F A016185 a(n) = 9*a(n-1) + 8^(n-1), a(0)=0. - _Vincenzo Librandi_, Feb 09 2011
%F A016185 a(n) = 17*a(n-1) - 72*a(n-2), a(0)=0, a(1)=1. - _Vincenzo Librandi_, Feb 09 2011
%F A016185 a(n) = A001019(n) - A001018(n). - _Alois P. Heinz_, Aug 19 2021
%t A016185 LinearRecurrence[{17,-72}, {0,1}, 31] (* _Vladimir Joseph Stephan Orlovsky_, Feb 09 2011 *)
%o A016185 (Magma) [9^n -8^n: n in [0..40]]; // _G. C. Greubel_, Nov 29 2024
%o A016185 (Python)
%o A016185 def A016185(n): return pow(9,n) - pow(8,n)
%o A016185 print([A016185(n) for n in range(41)]) # _G. C. Greubel_, Nov 29 2024
%Y A016185 Cf. A001018, A001019, A016140.
%K A016185 nonn,easy
%O A016185 0,3
%A A016185 _N. J. A. Sloane_