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A116837 Number of permutations of length n which avoid the patterns 3421, 4123, 4312; or avoid the patterns 2341, 3142, 3214. 0
1, 2, 6, 21, 73, 250, 853, 2911, 9938, 33931, 115849, 395534, 1350437, 4610679, 15741842, 53746011, 183500361, 626509422, 2139036965, 7303129015, 24934442130, 85131510491, 290657157705, 992365609838, 3388148123941 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
G.f.: A(x) = -x*(x-1)^3/((x^2-x+1)*(2*x^2-4*x+1)).
MATHEMATICA
CoefficientList[Series[-(x - 1)^3/((x^2 - x + 1) (2 x^2 - 4 x + 1)), {x, 0, 30}], x] (* Wesley Ivan Hurt, Dec 28 2023 *)
CROSSREFS
Sequence in context: A116760 A116828 A294764 * A116781 A047106 A360152
KEYWORD
nonn,easy
AUTHOR
Lara Pudwell, Feb 26 2006
STATUS
approved

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Last modified March 28 11:46 EDT 2024. Contains 371241 sequences. (Running on oeis4.)