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 A165246 #27 Jun 18 2025 00:59:00
%S A165246 7,17,117,1117,11117,111117,1111117,11111117,111111117,1111111117,
%T A165246 11111111117,111111111117,1111111111117,11111111111117,
%U A165246 111111111111117,1111111111111117,11111111111111117,111111111111111117,1111111111111111117,11111111111111111117,111111111111111111117
%N A165246 a(n) = (10^n + 53)/9.
%C A165246 a(n) are also n-1 units followed by a seven.
%H A165246 Markus Tervooren, <a href="https://factordb.com/index.php?query=%2810%5Ex%2B53%29%2F9">Factorizations of (1)w7</a>.
%H A165246 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F A165246 a(n) = 9*a(n-1) - 8*a(n-2) + 2*10^(n-2) for n>2, a(1)=7, a(2)=17. - _Vincenzo Librandi_, Aug 02 2010
%F A165246 From _Colin Barker_, Jan 24 2013: (Start)
%F A165246 a(n) = 11*a(n-1) - 10*a(n-2).
%F A165246 G.f.: -x*(60*x-7)/((x-1)*(10*x-1)). (End)
%F A165246 E.g.f.: -6 + exp(x)*(53 + exp(9*x))/9. - _Elmo R. Oliveira_, Jun 17 2025
%t A165246 Table[FromDigits[PadLeft[{7}, n, 1]], {n, 20}] (* _Harvey P. Dale_, Oct 17 2011 *)
%o A165246 (PARI) my(x='x+O('x^22)); Vec(x*(7-60*x)/((1-11*x+10*x^2))) \\ _Elmo R. Oliveira_, Jun 17 2025
%K A165246 nonn,easy
%O A165246 1,1
%A A165246 _Ivan Panchenko_, Sep 10 2009
%E A165246 More terms from _Elmo R. Oliveira_, Jun 17 2025