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A209184
Number of words, either empty or beginning with the first letter of the cyclic 5-ary alphabet, where each letter of the alphabet occurs n times and letters of neighboring word positions are equal or neighbors in the alphabet.
1
1, 2, 114, 12622, 1754954, 276049002, 46957069166, 8432879950182, 1576025367484986, 303680854369601602, 59946832651601518874, 12067737101428788147678, 2469034689095701731579766, 512096607962969119056789578, 107455511844928367137882085286
OFFSET
0,2
COMMENTS
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 (5*n-1)-step walks on 5-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 {1,5}.
CROSSREFS
Column k=5 of A208879.
Sequence in context: A157068 A008271 A362575 * A356724 A065670 A105327
KEYWORD
nonn,walk
AUTHOR
Alois P. Heinz, Mar 05 2012
STATUS
approved