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A209185
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Number of words, either empty or beginning with the first letter of the cyclic 6-ary alphabet, where each letter of the alphabet occurs n times and letters of neighboring word positions are equal or neighbors in the alphabet.
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1
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1, 2, 202, 53768, 19341130, 8151741752, 3795394507240, 1892725627422240, 992594962274742090, 540969426319412656280, 303934170379321788972952, 175019302819674622982714912, 102858166922334018149414066152, 61493440878115135100772134725088
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OFFSET
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0,2
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COMMENTS
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The first and the last letters are considered neighbors in a cyclic alphabet. The words are not considered cyclic here.
a(n) is also the number of (6*n-1)-step walks on 6-dimensional cubic lattice from (1,0,...,0) to (n,n,...,n) with positive unit steps in all dimensions such that the indices of dimensions used in consecutive steps differ by less than 2 or are in the set {1,6}.
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LINKS
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CROSSREFS
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KEYWORD
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nonn,walk
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AUTHOR
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STATUS
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approved
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