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A365559
Number of free n-polysticks (or polyedges) in 3 dimensions.
7
1, 2, 7, 28, 160, 1085, 8403, 69824, 607988, 5448444, 49846437
OFFSET
1,2
COMMENTS
a(1)-a(8) verified and a(9)-a(10) computed by John Mason.
LINKS
EXAMPLE
There are a(3) = 7 free 3-polysticks in 3 dimensions: A019988(3) = 5 properly 1- or 2-dimensional (straight, "U", "T", "L", and skew, similar to the 5 tetrominoes) and 2 properly 3-dimensional (one path-like and one with a vertex of degree 3).
CROSSREFS
Sum of first three columns of A365566.
Cf. A019988 (2 dimensions), A365560 (fixed), A365561 (4 dimensions), A365563 (5 dimensions), A365565 (arbitrary dimension).
14th row of A366766.
Sequence in context: A362084 A296726 A334613 * A123026 A013011 A013181
KEYWORD
nonn,hard,more
AUTHOR
EXTENSIONS
a(11) derived from Ishino Keiichiro's website (sum of 2-sided 2D-edges and 3D-edges), added by Pontus von Brömssen, Dec 21 2023
STATUS
approved