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 A238557 Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 8 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=4*floor(n/2), read by rows. 21

%I

%S 1,4,9,6,1,1,4,18,22,6,1,8,49,139,204,145,54,8,1,1,8,83,392,1056,1438,

%T 956,240,25,1,12,139,927,3731,8772,12069,9506,4366,1160,179,16,1,1,12,

%U 198,1742,9748,33644,73274,98779,80661,37886,9679,1258,72

%N Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 8 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=4*floor(n/2), read by rows.

%H Andrew Howroyd, <a href="/A238557/b238557.txt">Table of n, a(n) for n = 2..991</a>

%H Christopher Hunt Gribble, <a href="/A238009/a238009_1.cpp.txt">C++ program</a>

%F tabf,nonn

%e The first 4 rows of T(n,k) are:

%e .\ k 0 1 2 3 4 5 6 7 8

%e n

%e 2 1 4 9 6 1

%e 3 1 4 18 22 6

%e 4 1 8 49 139 204 145 54 8 1

%e 5 1 8 83 392 1056 1438 956 240 25

%Y Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550-A238552, A228166, A238555, A238556, A228167, A238558, A238559, A228168, A238581-A238583, A228169, A238586, A238592.

%K tabf,nonn

%O 2,2

%A _Christopher Hunt Gribble_, Feb 28 2014

%E Terms corrected and xrefs updated by _Christopher Hunt Gribble_, Apr 27 2015

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Last modified February 18 00:37 EST 2020. Contains 332006 sequences. (Running on oeis4.)