login
A238551
Number T(n,k) of equivalence classes of ways of placing k 3 X 3 tiles in an n X 6 rectangle under all symmetry operations of the rectangle; irregular triangle T(n,k), n>=3, 0<=k<=2*floor(n/3), read by rows.
10
1, 2, 1, 1, 2, 2, 1, 4, 4, 1, 4, 11, 3, 1, 1, 6, 21, 13, 4, 1, 6, 36, 32, 13, 1, 8, 54, 82, 49, 8, 1, 1, 8, 77, 165, 151, 44, 6, 1, 10, 103, 319, 382, 173, 31, 1, 10, 134, 530, 867, 559, 164, 12, 1, 1, 12, 168, 852, 1789, 1632, 705, 119, 9
OFFSET
3,2
LINKS
Christopher Hunt Gribble, C++ program
EXAMPLE
The first 12 rows of T(n,k) are:
.\ k 0 1 2 3 4 5 6 7 8
n
3 1 2 1
4 1 2 2
5 1 4 4
6 1 4 11 3 1
7 1 6 21 13 4
8 1 6 36 32 13
9 1 8 54 82 49 8 1
10 1 8 77 165 151 44 6
11 1 10 103 319 382 173 31
12 1 10 134 530 867 559 164 12 1
13 1 12 168 852 1789 1632 705 119 9
14 1 12 207 1255 3409 4074 2406 618 66
PROG
(C++) See Gribble link.
KEYWORD
tabf,nonn
AUTHOR
EXTENSIONS
Terms corrected and xrefs updated by Christopher Hunt Gribble, Apr 27 2015
Terms a(57) and beyond from Andrew Howroyd, May 29 2017
STATUS
approved