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A116808
Number of permutations of length n which avoid the patterns 1342, 3214, 4312.
0
1, 2, 6, 21, 71, 213, 569, 1389, 3175, 6927, 14632, 30238, 61596, 124335, 249598, 499492, 997953, 1992420, 3977093, 7939304, 15852025, 31658506, 63240940, 126356805, 252509950, 504690182, 1008848258, 2016839103, 4032297299
OFFSET
1,2
FORMULA
G.f.: A(x) = -{(5x^8-12x^7+3x^6+11x^5-26x^4+34x^3-22x^2+7x-1)x}/{(2x-1)(x-1)^6(x^2-1+x)}
CROSSREFS
Sequence in context: A294725 A116755 A116833 * A294726 A294700 A294701
KEYWORD
nonn,easy
AUTHOR
Lara Pudwell, Feb 26 2006
STATUS
approved