OFFSET
0,3
COMMENTS
Here is the 3-row parallelogram of length 6 (with 18 cells):
___ ___ ___ ___ ___ ___
| | | | | | |
_|___|___|___|___|_ _|___|
| | | | | | |
_|___|___|___|___|_ _|___|
| | | | | | |
|___|___|___|___|___|___|,
and here are the two types of (triangular and rectangular) tiles of size 3, which can be rotated as needed:
___
| |
_|___|_ ___________
| | | | | | |
|___|___|, |___|___|___|.
As an example, here is one of the a(6) = 107 ways to tile the 3 x 6 parallelogram:
___ _______ ___________
| | | |
_| _|_ _|___________|
| | | | |
_| _| |___|___________|
| | | |
|___|_______|___________|.
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,0,4,-1,0,-1).
FORMULA
MATHEMATICA
LinearRecurrence[{2, 0, 4, -1, 0, -1}, {1, 1, 2, 7, 17, 41}, 40]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Greg Dresden and Mingjun Oliver Ouyang, Aug 30 2024
STATUS
approved