A358709 a(n) is the number of free, tree-like polyiamonds, of size 3*n+1, with 120-degree rotational symmetry formed of a central triangle and identical, non-intersecting snakes leading from each of its sides.

1, 1, 1, 2, 3, 6, 11, 20, 37, 66, 119, 217, 391, 706, 1274, 2289, 4133, 7435, 13384, 24068

Offset

0,4

Links

Table of n, a(n) for n=0..19.

John Mason, Illustrations

Crossrefs

Sequence in context: A010033 A065615 A054182 * A346736 A335628 A355560

Adjacent sequences: A358706 A358707 A358708 * A358710 A358711 A358712

Keyword

nonn,more

Author

John Mason, Jan 10 2023

Status

approved