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.

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, 956, 240, 25, 1, 12, 139, 927, 3731, 8772, 12069, 9506, 4366, 1160, 179, 16, 1, 1, 12, 198, 1742, 9748, 33644, 73274, 98779, 80661, 37886, 9679, 1258, 72

Offset: 2

Author

Christopher Hunt Gribble, Feb 28 2014

Keywords

• tabf
• nonn

Examples

			The first 4 rows of T(n,k) are:
.\ k  0     1     2     3     4     5     6     7     8
n
2     1     4     9     6     1
3     1     4    18    22     6
4     1     8    49   139   204   145    54     8     1
5     1     8    83   392  1056  1438   956   240    25
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 2..991
• Christopher Hunt Gribble, C++ program

Crossrefs

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.

Formula

tabf,nonn

Extensions

Terms corrected and xrefs updated by Christopher Hunt Gribble, Apr 27 2015