OFFSET
1,2
LINKS
Moa Apagodu (formerly Mohamud Mohammed) and Stirling Chow, Counting hexagonal lattice animals confined to a strip, arXiv:math/0202295v5 [math.CO], 2009. See Section 7.
Moa Apagodu, Counting Hexagonal Lattice Animals Using Umbral-Transfer-Matrix Method [dead link]
Moa Apagodu, Maple programs.
EXAMPLE
This sequence first diverges from A059716 at n = 4. a(4) is 2 greater than A059716(4) because a(4) counts the following 2 fixed polyhexes of 4 cells that contain a column with two contiguous blocks of cells:
_ _
_/ \ / \_
/ \_/ \_/ \
\_/ \_/
/ \_ _/ \
\_/ \ / \_/
\_/ \_/
This sequence first diverges from A001207 at n = 7. a(7) is 4 less than A001207(7) because a(7) does not count the following 4 fixed polyhexes of 7 cells that contain a column with more than two contiguous blocks of cells:
_ _ _ _
_/ \ / \_ _/ \ / \_
/ \_/ \_/ \ / \_/ \_/ \
\_/ \_/ \_/ \_/
/ \_ _/ \ / \_ _/ \
\_/ \ / \_/ \_/ \_ _/ \_/
/ \_/ \_/ \ \_/ \ / \_/
\_/ \_/ \_/ \_/
/ \_ _/ \ _/ \ / \_
\_/ \ / \_/ / \_/ \_/ \
\_/ \_/ \_/ \_/
MAPLE
The sequence is generated by a Maple program that accompanies the paper "Counting Hexagonal Lattice Animals using Umbral-Transfer-Matrix Method (UTMM)"
KEYWORD
hard,more,nonn
AUTHOR
Moa Apagodu, Mar 22 2002 and Oct 31 2002
STATUS
approved