A238555 Number T(n,k) of equivalence classes of ways of placing k 2 X 2 tiles in an n X 7 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=2, 0<=k<=3*floor(n/2), read by rows.

1, 3, 6, 2, 1, 3, 12, 8, 1, 6, 34, 68, 72, 30, 6, 1, 6, 58, 206, 403, 336, 106, 1, 9, 98, 509, 1551, 2505, 2196, 971, 219, 20, 1, 9, 140, 980, 4248, 10592, 15614, 12876, 5462, 900, 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 6 rows of T(n,k) are:
./ k  0     1     2     3     4     5     6     7     8     9
n
2     1     3     6     2
3     1     3    12     8
4     1     6    34    68    72    30     6
5     1     6    58   206   403   336   106
6     1     9    98   509  1551  2505  2196   971   219    20
7     1     9   140   980  4248 10592 15614 12876  5462   900
		

Links

• Andrew Howroyd, Table of n, a(n) for n = 2..953
• Christopher Hunt Gribble, C++ program

Crossrefs

Cf. A034851, A226048, A102541, A226290, A238009, A228570, A225812, A238189, A238190, A228572, A228022, A231145, A231473, A231568, A232440, A228165, A238550, A238551, A238552, A228166, A238556, A228167, A238557, A238558, A238559, A228168, A238581, A238582, A238583, A228169, A238586, A238592.

Extensions

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