|
|
A228166
|
|
Irregular triangle read by rows: T(n,k) is the number of binary pattern classes in the (7,n)-rectangular grid with k '1's and (7n-k) '0's: two patterns are in same class if one of them can be obtained by a reflection or 180-degree rotation of the other.
|
|
30
|
|
|
1, 1, 4, 12, 19, 19, 12, 4, 1, 1, 4, 28, 94, 266, 508, 777, 868, 777, 508, 266, 94, 28, 4, 1, 1, 8, 65, 363, 1574, 5231, 13826, 29454, 51408, 74130, 88900, 88900, 74130, 51408, 29454, 13826, 5231, 1574, 363, 65, 8, 1, 1, 8, 106, 832, 5199, 24648, 94524, 296296, 777997, 1727440, 3282774, 5369832, 7608483, 9362256, 10032648, 9362256
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,3
|
|
COMMENTS
|
The length of row n is 7*n+1.
Sum of rows (see example) gives A225831.
Also the number of equivalence classes of ways of placing k 1 X 1 tiles in an n X 7 rectangle under all symmetry operations of the rectangle. - Christopher Hunt Gribble, Apr 24 2015
|
|
LINKS
|
|
|
EXAMPLE
|
Irregular triangle:
1
1 4 12 19 19 12 4 1
1 4 28 94 266 508 777 868 777 508 266 94 28 4 1
1 8 65 363 1574 5231 13826 29454 51408 74130 88900 88900 74130 51408 29454 13826 5231 1574 363 65 8 1
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,tabf
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|