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 A172174 #21 Mar 04 2024 01:13:26 %S A172174 1,91,8191,737191,66347191,5971247191,537412247191,48367102247191, %T A172174 4353039202247191,391773528202247191,35259617538202247191, %U A172174 3173365578438202247191,285602902059438202247191,25704261185349438202247191,2313383506681449438202247191 %N A172174 a(n) = 90*a(n-1) + 1. %C A172174 Difference of pairs of integers given in A162849. %C A172174 Sum of digits give A017173. %H A172174 Colin Barker, <a href="/A172174/b172174.txt">Table of n, a(n) for n = 1..512</a> %H A172174 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (91,-90). %F A172174 From _Colin Barker_, Oct 02 2015: (Start) %F A172174 a(n) = 91*a(n-1) - 90*a(n-2) for n>2. %F A172174 G.f.: 1 / ((1-x)*(1-90*x)). (End) %t A172174 NestList[90#+1&,1,20] (* _Harvey P. Dale_, Aug 29 2014 *) %o A172174 (PARI) Vec(1/((x-1)*(90*x-1)) + O(x^30)) \\ _Colin Barker_, Oct 02 2015 %o A172174 (SageMath) [(90^n -1)/89 for n in (1..50)] # _G. C. Greubel_, Apr 26 2022 %Y A172174 Cf. A017173, A162849, A165154. %K A172174 nonn,easy %O A172174 1,2 %A A172174 _Mark Dols_, Jan 28 2010