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 A015209 #19 May 14 2019 11:10:42
%S A015209 1,2,21,688,123827,72470454,234124353817,2465349491066876,
%T A015209 143340549850680842079,27168340876252989570097858,
%U A015209 28432984085878392152571573148709,97003727566351469067244149247119170952
%N A015209 Sum of Gaussian binomial coefficients for q=18.
%D A015209 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 A015209 I. P. Goulden and D. M. Jackson, Combinatorial Enumeration. Wiley, NY, 1983, p. 99.
%D A015209 M. Sved, Gaussians and binomials, Ars. Combinatoria, 17A (1984), 325-351.
%H A015209 Vincenzo Librandi, <a href="/A015209/b015209.txt">Table of n, a(n) for n = 0..50</a>
%H A015209 Kent E. Morrison, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL9/Morrison/morrison37.html">Integer Sequences and Matrices Over Finite Fields</a>, Journal of Integer Sequences, Vol. 9 (2006), Article 06.2.1.
%F A015209 a(0) = 1, a(1) = 2, a(n) = 2*a(n-1) + a(n-2)*((18^(n-1)) - 1). - _Vincenzo Librandi_, Nov 02 2012
%t A015209 Total/@Table[QBinomial[n, m, 18], {n, 0, 20}, {m, 0, n}] (* _Vincenzo Librandi_, Nov 02 2012 *)
%Y A015209 Row sums of triangle A022182.
%K A015209 nonn
%O A015209 0,2
%A A015209 _N. J. A. Sloane_, _Olivier Gérard_