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A177560
Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, up.
0
1, 6, 84, 2054, 78231, 4290094, 320821079, 31414709469, 3903342922319, 600255674485509, 111949642485388109, 24900064681761042208, 6512262064364063116565, 1978717544093002418592533
(list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Table of n, a(n) for n=1..14.
CROSSREFS
Sequence in context: A147626 A123312 A010794 * A177562 A273935 A318399
Adjacent sequences: A177557 A177558 A177559 * A177561 A177562 A177563
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 10 2010
EXTENSIONS
a(11)-a(14) from Alois P. Heinz, Nov 02 2013
STATUS
approved

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Last modified November 29 00:35 EST 2024. Contains 378208 sequences.
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