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A177636
Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down.
0
1, 26, 2506, 624446, 322530466, 301458657626, 465560613932206, 1112284734271280846
OFFSET
1,2
CROSSREFS
Sequence in context: A363990 A201623 A087616 * A232159 A263946 A358164
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 10 2010
EXTENSIONS
a(8) from Alois P. Heinz, Oct 22 2013
STATUS
approved