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 A015257 #27 Sep 08 2022 08:44:39
%S A015257 1,31,1147,41107,1480963,53308003,1919128099,69088371619,
%T A015257 2487182817955,89538572808355,3223388672928931,116041991914472611,
%U A015257 4177511710786827427,150390421577130906787,5414055176843881927843,194905986365976733701283
%N A015257 Gaussian binomial coefficient [ n,2 ] for q = -6.
%D A015257 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 A015257 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p. 99.
%D A015257 M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.
%H A015257 Vincenzo Librandi, <a href="/A015257/b015257.txt">Table of n, a(n) for n = 2..200</a>
%H A015257 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (31,186,-216).
%F A015257 G.f.: x^2/((1-x)*(1+6*x)*(1-36*x)).
%F A015257 a(2) = 1, a(3) = 31, a(4) = 1147, a(n) = 31*a(n-1) + 186*a(n-2) - 216*a(n-3). - _Vincenzo Librandi_, Oct 27 2012
%t A015257 Table[QBinomial[n, 2, -6], {n, 2, 20}] (* _Vincenzo Librandi_, Oct 27 2012 *)
%o A015257 (Sage) [gaussian_binomial(n,2,-6) for n in range(2,17)] # _Zerinvary Lajos_, May 27 2009
%o A015257 (Magma) I:=[1, 31, 1147]; [n le 3 select I[n] else 31*Self(n-1) + 186*Self(n-2) - 216*Self(n-3): n in [1..30]]; // _Vincenzo Librandi_, Oct 27 2012
%K A015257 nonn,easy
%O A015257 2,2
%A A015257 _Olivier Gérard_, Dec 11 1999