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 A015253 #30 Sep 08 2022 08:44:39
%S A015253 1,13,221,3485,55965,894621,14317213,229062301,3665049245,58640578205,
%T A015253 938250090141,15011998086813,240191982810781,3843071671285405,
%U A015253 61489146955314845,983826350426044061,15741221610252678813
%N A015253 Gaussian binomial coefficient [ n,2 ] for q = -4.
%D A015253 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 A015253 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p. 99.
%D A015253 M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.
%H A015253 Vincenzo Librandi, <a href="/A015253/b015253.txt">Table of n, a(n) for n = 2..200</a>
%H A015253 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (13,52,-64).
%F A015253 G.f.: x^2/((1-x)*(1+4*x)*(1-16*x)).
%F A015253 a(2) = 1, a(3) = 13, a(4) = 221 a(n) = 13*(n-1) + 52*a(n-2) - 64*a(n-3). - _Vincenzo Librandi_, Oct 27 2012
%e A015253 G.f. = x^2 + 13*x^3 + 221*x^4 + 3485*x^5 + 55965*x^6 + 894621*x^7 + ...
%t A015253 Rest[Table[QBinomial[n,2,-4],{n,20}]] (* _Harvey P. Dale_, Feb 26 2012 *)
%o A015253 (Sage) [gaussian_binomial(n,2,-4) for n in range(2,19)] # _Zerinvary Lajos_, May 27 2009
%o A015253 (Magma) I:=[1, 13, 221]; [n le 3 select I[n] else 13*Self(n-1) + 52*Self(n-2) - 64*Self(n-3): n in [1..30]]; // _Vincenzo Librandi_, Oct 27 2012
%K A015253 nonn,easy
%O A015253 2,2
%A A015253 _Olivier Gérard_, Dec 11 1999