A238557 - OEIS

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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.

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

(list; graph; refs; listen; history; text; internal format)

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

2 1 4 9 6 1