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 A179619 #18 Jun 02 2025 03:02:00
%S A179619 1,13,135,1357,13579,135801,1358023,13580245,135802467,1358024689,
%T A179619 13580246911,135802469133,1358024691355,13580246913577,
%U A179619 135802469135799,1358024691358021,13580246913580243,135802469135802465,1358024691358024687,13580246913580246909
%N A179619 a(1)=1, a(n+1) = 10*a(n)+2*n-1.
%C A179619 Third column of A164851. The repeating pattern corresponds to the decimal expansion of 11/81 = 0.13580246913580246...
%H A179619 Colin Barker, <a href="/A179619/b179619.txt">Table of n, a(n) for n = 1..1000</a>
%H A179619 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (12,-21,10).
%F A179619 a(1)=1, a(2)=13, a(3)=135, a(n) = 12*a(n-1)-21*a(n-2)+10*a(n-3). - _Harvey P. Dale_, Aug 16 2012
%F A179619 G.f.: -x*(x+1) / ((x-1)^2*(10*x-1)). - _Colin Barker_, Oct 03 2015
%t A179619 RecurrenceTable[{a[1] == 1, a[n] == 10 a[n - 1] + 2 n - 1}, a, {n,
%t A179619 30}] (* or *) LinearRecurrence[{12,-21,10},{1,13,135},30] (* _Harvey P. Dale_, Aug 16 2012 *)
%o A179619 (PARI) Vec(-x*(x+1)/((x-1)^2*(10*x-1)) + O(x^30)) \\ _Colin Barker_, Oct 03 2015
%Y A179619 Cf. A164851.
%K A179619 nonn,easy
%O A179619 1,2
%A A179619 _Mark Dols_, Jul 20 2010