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A177518 Number of permutations of 1..n avoiding adjacent step pattern up, down, down, down. 3
1, 2, 6, 24, 116, 672, 4536, 34944, 302896, 2916992, 30899616, 357080064, 4470310976, 60269056512, 870591770496, 13414154256384, 219604379097856, 3806644208863232, 69650568655858176, 1341477655028219904, 27128858382696129536, 574755293400886321152 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..175

FORMULA

a(n) ~ c * n! / r^n, where r = 1.03841563726655630653502212237531835609230623619708108964...  is the root of the equation cos(r) - sin(r) + exp(-r) = 0, and c = 1.1718801964367046779834894478269895859267745270209175... . - Vaclav Kotesovec, Aug 21 2014

CROSSREFS

Column k=0 of A242820.

Columns k=8,14 of A242784.

Sequence in context: A324130 A324131 A221988 * A319027 A228397 A164871

Adjacent sequences:  A177515 A177516 A177517 * A177519 A177520 A177521

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 10 2010

EXTENSIONS

a(18)-a(22) from Alois P. Heinz, Oct 06 2013

STATUS

approved

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Last modified April 24 22:26 EDT 2019. Contains 322446 sequences. (Running on oeis4.)