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A332921 Number of symmetric non-isomorphic free unrooted snake-shaped polyominoes of maximum length on a quadratic board of n X n squares. 3
1, 1, 2, 3, 2, 0, 3, 0, 2, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Polyominoes only differing by any combination of translation, rotation and reflection are counted only once.

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

a(1) = 1 (L = A331968(1) = 1):

X

.

a(2) = 1 (L = 3):

X O

. X

.

a(3) = 2 (L = 7):

X O O . X O

. . O X . O

X O O O O O

.

a(4) = 3 (L = 11)

. X O . . X O O . X O O

X . O O X . . O X . . O

O O . O O . . O O . O O

. O O O O O O O O O O .

.

a(5) = 2 (L = 17)

O O O O X O O O O O

O . . . . O . . . O

O O O O O O O . O O

. . . . O . O . O .

X O O O O X O . O X

.

a(7) = 3 (L = 33)

O O O . O O O O O X . O O O O O O . O O O

O . O . O . O O . . O O . O O . O O O . O

O . O O O . O O O . O . O O O O . . . O O

O O . . . O O . O . O . O . . O O . O O .

. O O . O O . O O . O . O O X . O . O . x

X . O . O . X O . O O . . O O . O . O . O

O O O . O O O O O O . X O O O O O . O O O

.

a(9) = 2 (L = 53)

. O X . O O O O O O O X . O O O O O

O O . O O . . . O O . . O O . . . O

O . O O . O O O O O . O O . O O O O

O . O . O O . . . O . O . O O . . .

O O O . O . O O O O O O . O . . . .

. . . O O . O . O . . . O O . O O O

O O O O . O O . O O O O O . O O . O

O . . . O O . O O O . . . O O . . O

O O O O O . X O . O O O O O . X O O

CROSSREFS

Cf. A331968, A331986, A332920.

Sequence in context: A324300 A323695 A303121 * A239579 A165192 A104771

Adjacent sequences: A332918 A332919 A332920 * A332922 A332923 A332924

KEYWORD

nonn,hard,more

AUTHOR

Hugo Pfoertner, Mar 05 2020

STATUS

approved

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Last modified March 21 18:35 EDT 2023. Contains 361410 sequences. (Running on oeis4.)