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A177556 Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, down. 0
1, 6, 78, 1735, 59246, 2885772, 190320239, 16347310234, 1774441830858, 237627036224047, 38497690772499518, 7423393488778249536, 1680457375599950641631, 441370935373373671881586 (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: A162656 A332680 A179498 * A219435 A219135 A208308

Adjacent sequences:  A177553 A177554 A177555 * A177557 A177558 A177559

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 October 25 04:28 EDT 2021. Contains 348237 sequences. (Running on oeis4.)