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 A329707 #16 Jun 19 2024 07:40:40
%S A329707 1,2,4,11,25,61,146,351,844,2028,4875,11717,28163,67692,162703,391070,
%T A329707 939968,2259289,5430383,13052363,31372406,75406105,181244648,
%U A329707 435636112,1047086489,2516756727,6049227537,14539805696,34947594281,83999358146,201899224084,485281049587,1166412095721
%N A329707 Number of placements of zero or more dominoes on a 2 X n grid where no two empty squares are horizontally adjacent.
%H A329707 Andrew Howroyd, <a href="/A329707/b329707.txt">Table of n, a(n) for n = 0..1000</a>
%H A329707 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,0,0,0,-1).
%F A329707 a(n) = 2*a(n-1) + a(n-2) - a(n-6) for n > 6.
%F A329707 G.f.: (1 - x)*(1 + x + x^3)/(1 - 2*x - x^2 + x^6).
%t A329707 LinearRecurrence[{2, 1, 0, 0, 0, -1}, {1, 2, 4, 11, 25, 61}, 50] (* _Paolo Xausa_, Jun 19 2024 *)
%o A329707 (PARI) Vec((1 - x)*(1 + x + x^3)/(1 - 2*x - x^2 + x^6) + O(x^30))
%Y A329707 Row 2 of A332862.
%K A329707 nonn
%O A329707 0,2
%A A329707 _Andrew Howroyd_, Feb 28 2020