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 A164827 #33 Jun 02 2025 01:52:39
%S A164827 2,1,21,31,241,551,2961,8471,38081,122791,503601,1731511,6767521,
%T A164827 24082631,91757841,332584151,1250162561,4576004071,17077629681,
%U A164827 62837670391,233613967201,861990671111,3198130343121,11818037054231
%N A164827 Generalized Lucas numbers: a(n) = a(n-1) + 10*a(n-2); with a(1)=2 a(2)=1.
%H A164827 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1,10).
%F A164827 G.f.: x*(2-x)/(1-x-10*x^2). - _Colin Barker_, Jun 17 2012
%F A164827 a(n) = a(n-1) + 10*a(n-2); a(1)=2, a(2)=1. - _Harvey P. Dale_, Apr 07 2015
%F A164827 a(n) = 2*A015446(n-1) - A015446(n-2). - _R. J. Mathar_, Oct 08 2016
%t A164827 LinearRecurrence[{1,10},{2,1},30] (* _Harvey P. Dale_, Apr 07 2015 *)
%Y A164827 Cf. A000032, A015446.
%K A164827 nonn,easy
%O A164827 1,1
%A A164827 _Mark Dols_, Aug 27 2009