%I #22 Jun 06 2024 12:28:24

%S 2,12,88,710,6054,53500,484784,4475010,41902626,396838992,3793117200,

%T 36534684066

%N a(n) is the number of fixed polyglasses (polyiamonds which need only touch at corners) with n cells.

%C 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.

%H David Bevan, <a href="/A319324/a319324.png">The 88 fixed triglasses.</a>

%H Rebecca M. Bowen, Sadie Pruitt, and Douglas A. Torrance, <a href="https://arxiv.org/abs/2405.20793">Properties of regular Tangles</a>, arXiv:2405.20793 [math.CO], 2024. See p. 2.

%H Adam Gruber, <a href="https://devweb3000.cis.strath.ac.uk/~xpb16190/LatticeAnimals/LatticeAnimals.jar">Java program to count lattice animals</a>.

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

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

%K nonn,more,hard

%O 1,1

%A _David Bevan_, Sep 18 2018

%E a(12) from _Aaron N. Siegel_, May 22 2022