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A202216
Number of permutations avoiding the consecutive pattern 34521.
1
1, 2, 6, 24, 119, 708, 4914, 38976, 347775, 3447912, 37601586, 447346944, 5765604885, 80025786960, 1190085736014, 18877969022976, 318171464604945, 5677939605422880, 106955077375109430, 2120744934976978944, 44153462828412744975, 963040357207773472320
OFFSET
1,2
COMMENTS
a(n) is the number of permutations on [n] that avoid the consecutive pattern 34521. It is the same as the number of permutations which avoid 12453, 31245, 35421, 54213, 12543, 32145 or 54123.
CROSSREFS
KEYWORD
nonn
AUTHOR
Ray Chandler, Dec 14 2011
STATUS
approved