A238556 - OEIS

A238556

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

1, 3, 2, 1, 3, 4, 1, 6, 9, 1, 6, 21, 13, 4, 1, 9, 39, 53, 23, 1, 9, 64, 128, 87, 1, 12, 95, 283, 311, 91, 10, 1, 12, 133, 521, 891, 543, 106, 1, 15, 177, 917, 2118, 2030, 646, 1, 15, 228, 1444, 4424, 6000, 3295, 456, 25, 1, 18, 285, 2207, 8408, 15484, 13106, 4322, 473

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

OFFSET

3,2

LINKS

Andrew Howroyd, Table of n, a(n) for n = 3..971

Christopher Hunt Gribble, C++ program

EXAMPLE

The first 5 rows of T(n,k) are:

./ k 0 1 2 3 4 5 6

3 1 3 2

4 1 3 4

5 1 6 9