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A180437 a(n) counts the distinct cubical (on alphabet of 3 symbols) billiard words with length n, acting as prefix to just k = 1 such word of length n+1 (that is, not "special"). 3
0, 0, 0, 6, 24, 78, 186, 372, 876, 1632, 3024, 5310, 8496, 13344, 21186, 31878, 46752, 66936, 94800, 130194 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,4
COMMENTS
By symmetry under reversal, a(n) also counts length n cubical billiard words acting as suffix to just k length n+1 cubical billiard words. The attached program counts k-special words for k = 1,...,m, where m = 3 denotes the size of the alphabet.
LINKS
Fred Lunnon, Magma program
PROG
(Magma) (see Links)
CROSSREFS
Sequence in context: A257956 A341364 A080373 * A276179 A162583 A259662
KEYWORD
nonn,more
AUTHOR
Fred Lunnon, Sep 05 2010
STATUS
approved

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Last modified February 21 12:33 EST 2024. Contains 370235 sequences. (Running on oeis4.)