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A319324 a(n) is the number of fixed polyglasses (polyiamonds which need only touch at corners) with n cells. 4
2, 12, 88, 710, 6054, 53500, 484784, 4475010, 41902626, 396838992, 3793117200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Polyglasses are to polyiamonds (A001420) as polyplets (A006770) are to polyominoes (A001168). The name derives from the 2-celled animal (diglass) which looks like an hourglass.

LINKS

Table of n, a(n) for n=1..11.

David Bevan, The 88 fixed triglasses.

Adam Gruber, Java program to count lattice animals.

EXAMPLE

a(2) = 12: three rotations of a diamond, three rotations of an hourglass and six rotations of "two mountains".

CROSSREFS

Cf. A001420 (fixed polyiamonds), A319325 (row convex polyglasses), A319326 (column convex polyglasses).

Sequence in context: A181345 A193125 A305868 * A059435 A192621 A143923

Adjacent sequences:  A319321 A319322 A319323 * A319325 A319326 A319327

KEYWORD

nonn,more

AUTHOR

David Bevan, Sep 18 2018

STATUS

approved

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Last modified August 1 03:05 EDT 2021. Contains 346379 sequences. (Running on oeis4.)