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A177642
Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, down, up.
0
1, 70, 28854, 39663852, 137560321238, 1013521185982046, 14098691799360001768, 339727163188995946031850
OFFSET
1,2
CROSSREFS
Sequence in context: A274646 A005983 A200313 * A177644 A146499 A177649
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 10 2010
EXTENSIONS
a(8) from Alois P. Heinz, Nov 02 2013
STATUS
approved