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A177643
Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, up, down
0
1, 60, 21524, 26227974, 81550349446, 541799718812754, 6819616215236462578
OFFSET
1,2
CROSSREFS
Sequence in context: A003794 A275051 A068295 * A123482 A263606 A220371
KEYWORD
nonn
AUTHOR
R. H. Hardin May 10 2010
STATUS
approved