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A321114
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Number of permutations p of [n] such that in 0p the largest up-jump equals seven and no down-jump is larger than 2.
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2
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74, 528, 3550, 23284, 151096, 974472, 6252218, 39892080, 253727936, 1611713082, 10230277342, 64911693746, 411813289010, 2612751224650, 16579665387410, 105238154698686, 668214471729004, 4244427360639456, 26970709343926262, 171451330997483406, 1090351846894142818
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OFFSET
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7,1
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LINKS
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MAPLE
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b:= proc(u, o, k) option remember; `if`(u+o=0, 1,
add(b(u-j, o+j-1, k), j=1..min(2, u))+
add(b(u+j-1, o-j, k), j=1..min(k, o)))
end:
a:= n-> (k-> b(0, n, k)-b(0, n, k-1))(7):
seq(a(n), n=7..30);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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