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A165960 Number of permutations of length n without modular 3-sequences. 5
1, 1, 2, 3, 20, 100, 612, 4389, 35688, 325395, 3288490, 36489992, 441093864, 5770007009, 81213878830, 1223895060315, 19662509071056, 335472890422812, 6057979285535388, 115434096553014565, 2314691409652237700, 48723117262650147387, 1074208020519710570054 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Modular 3-sequences are of the following form: i,i+1,i+2, where arithmetic is modulo n.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..450

FORMULA

a(n) = n * A165961(n).

EXAMPLE

For n=3 the a(3) = 3 solutions are (0,2,1), (1,0,2) and (2,1,0).

CROSSREFS

Cf. A002628, A165961, A165962.

Sequence in context: A052804 A267652 A258089 * A125763 A042441 A128977

Adjacent sequences:  A165957 A165958 A165959 * A165961 A165962 A165963

KEYWORD

nonn

AUTHOR

Isaac Lambert, Oct 01 2009

EXTENSIONS

a(0)-a(2) and a(15)-a(22) from Alois P. Heinz, Apr 14 2021

STATUS

approved

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Last modified August 9 21:08 EDT 2022. Contains 356026 sequences. (Running on oeis4.)