A177294 - OEIS

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A177294

Number of permutations of 3 copies of 1..n with all adjacent differences <= 4 in absolute value.

0

1, 1, 20, 1680, 369600, 168168000, 41494252800, 6923871998400, 983114244363720, 139528504017728552

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OFFSET

0,3

COMMENTS

a(n) = (3n)!/6^n for n<=5.

LINKS

Table of n, a(n) for n=0..9.

CROSSREFS

Sequence in context: A177617 A177629 A177630 * A177615 A177616 A177295

Adjacent sequences: A177291 A177292 A177293 * A177295 A177296 A177297

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 06 2010

STATUS

approved