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 A015261 #24 Sep 08 2022 08:44:39
%S A015261 1,91,9191,918191,91828191,9182728191,918273728191,91827363728191,
%T A015261 9182736463728191,918273645463728191,91827364555463728191,
%U A015261 9182736455455463728191,918273645546455463728191
%N A015261 Gaussian binomial coefficient [ n,2 ] for q = -10.
%D A015261 J. Goldman and G.-C. Rota, The number of subspaces of a vector space, pp. 75-83 of W. T. Tutte, editor, Recent Progress in Combinatorics. Academic Press, NY, 1969.
%D A015261 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p. 99.
%D A015261 M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.
%H A015261 Vincenzo Librandi, <a href="/A015261/b015261.txt">Table of n, a(n) for n = 2..200</a>
%H A015261 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (91,910,-1000).
%F A015261 G.f.: x^2/((1-x)*(1+10*x)*(1-100*x)).
%F A015261 a(2) = 1, a(3) = 91, a(4) = 9191, a(n) = 91*a(n-1) + 910*a(n-2) - 1000*a(n-3). - _Vincenzo Librandi_, Oct 28 2012
%t A015261 Table[QBinomial[n, 2, -10], {n, 2, 20}] (* _Vincenzo Librandi_, Oct 28 2012 *)
%o A015261 (Sage) [gaussian_binomial(n,2,-10) for n in range(2,15)] # _Zerinvary Lajos_, May 27 2009
%o A015261 (Magma) I:=[1, 91, 9191]; [n le 3 select I[n] else 91*Self(n-1) + 910*Self(n-2) - 1000*Self(n-3): n in [1..20]]; // _Vincenzo Librandi_, Oct 28 2012
%K A015261 nonn,easy
%O A015261 2,2
%A A015261 _Olivier Gérard_, Dec 11 1999