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A165963 Number of permutations of length n without increasing or decreasing modular 3-sequences 5
0, 16, 80, 516, 3794, 31456, 290970, 2974380, 33311520, 405773448, 5342413414, 75612301688 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

COMMENTS

Increasing modular 3-sequences are of the following form: i,i+1,i+2, where arithmetic is modulo n, while correspondingly decreasing modular 3-sequences are of the form i,i-1,i-2, where arithmetic is modulo n.

LINKS

Table of n, a(n) for n=3..14.

FORMULA

Let b(n) be the sequence A165964. Then this sequence a(n)=n(b(n)).

EXAMPLE

For n=4 there are a(4)=16 solutions, thus there are 4!-a(4)=8 permutations of length 4 with increasing or decreasing modular 3-sequences. These are the permutations (0,1,2,3), (0,3,2,1), (1,2,3,0), (1,0,3,2), (2,3,0,1), (2,1,0,3), (3,0,1,2), and (3,2,1,0).

CROSSREFS

Cf. A095816, A165964, A078628.

Sequence in context: A068778 A247817 A034570 * A221910 A069840 A000817

Adjacent sequences:  A165960 A165961 A165962 * A165964 A165965 A165966

KEYWORD

nonn

AUTHOR

Isaac Lambert, Oct 07 2009

STATUS

approved

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Last modified December 22 18:48 EST 2014. Contains 252365 sequences.