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A177559 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down, down. 0
1, 6, 90, 2448, 105218, 6572088, 562874958, 63344668632, 9067009872984, 1608913338743280, 346665863545391736, 89160540714537206616, 26982910637581823115028, 9492077262717161359915632 (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: A177580 A177587 A177585 * A177581 A177566 A177586
Adjacent sequences: A177556 A177557 A177558 * A177560 A177561 A177562
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 May 14 10:07 EDT 2024. Contains 372532 sequences. (Running on oeis4.)