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

2,2

Links

Andrew Howroyd, Table of n, a(n) for n = 2..991

Christopher Hunt Gribble, C++ program

Formula

tabf,nonn

Example

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

Prog

(C++) See Gribble link.

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.

Sequence in context: A218358 A340127 A196403 * A271181 A338146 A338142

Adjacent sequences: A238554 A238555 A238556 * A238558 A238559 A238560

Keyword

tabf,nonn

Author

Christopher Hunt Gribble, Feb 28 2014

Extensions

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

Status

approved