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 A071333 #11 Feb 22 2020 08:30:16
%S A071333 0,0,0,0,0,0,1,0,21,107,619,1300,6740,19812,61075,181036,577551,
%T A071333 1626183,4904626,14071461,41336066,120630534,352200161,1023454347,
%U A071333 2997105957,8761810505,25648786717,75161609591,220583137840,647825855933
%N A071333 Number of polyiamonds with n cells that do not tile the plane.
%D A071333 M. Gardner, Tiling with Polyominoes, Polyiamonds and Polyhexes. Chap. 14 in Time Travel and Other Mathematical Bewilderments. New York: W. H. Freeman, pp. 175-187, 1988.
%H A071333 Joseph Myers, <a href="http://www.polyomino.org.uk/mathematics/polyform-tiling/">Polyiamond tiling</a>
%t A071333 A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {_, _}][[All, 2]]];
%t A071333 A000577 = A@000577;
%t A071333 A071332 = A@071332;
%t A071333 a[n_] := A000577[[n]] - A071332[[n]];
%t A071333 a /@ Range[30] (* _Jean-François Alcover_, Feb 21 2020 *)
%Y A071333 Equals A000577(n)-A071332(n) and A070764(n)+A071334(n). Cf. A054360, A070767.
%K A071333 hard,nonn
%O A071333 1,9
%A A071333 _Joseph Myers_, May 19 2002
%E A071333 More terms from _Joseph Myers_, Nov 11 2003
%E A071333 a(29) and a(30) from _Joseph Myers_, Nov 21 2010