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 A163437 #7 Dec 23 2016 21:17:47
%S A163437 1,7,322,51472,29671936,64588152832,545697103347712,
%T A163437 18161310923858378752,2399054119350722118025216,
%U A163437 1262710910458264839283982467072,2653270028014955753823799266500411392
%N A163437 Number of different fixed (possibly) disconnected polyominoes (of any area) bounded tightly by an n X n square.
%H A163437 G. C. Greubel, <a href="/A163437/b163437.txt">Table of n, a(n) for n = 1..55</a>
%F A163437 a(n) = 2^(n^2) - 4*2^((n-1)*n) + 4*2^((n-1)^2) + 2*2^((n-2)*n) - 4*2^((n-2)*(n-1)) + 2^((n-2)^2).
%e A163437 a(2)=7: 2 rotations of the strictly disconnected domino consisting of two squares connected at a vertex, 4 rotations of the L tromino, and the square tetromino.
%t A163437 Table[2^(n^2) - 4*2^((n - 1)*n) + 4*2^((n - 1)^2) + 2*2^((n - 2)*n) -
%t A163437 4*2^((n - 2)*(n - 1)) + 2^((n - 2)^2), {n, 1, 25}] (* _G. C. Greubel_, Dec 23 2016 *)
%Y A163437 Cf. A162677 (bound not necessarily tight), A163433 (fixed disconnected trominoes), A163434 (fixed disconnected tetrominoes), A163435 (fixed disconnected pentominoes), A163436 (fixed disconnected n-ominoes).
%K A163437 nonn
%O A163437 1,2
%A A163437 _David Bevan_, Jul 28 2009