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Search: id:A161128
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| A161128 |
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a(n) = n!*(1/1 + 1/2 + ... + 1/n) - (1! + 2! + ... + n!). |
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+0
2
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| 0, 0, 0, 2, 17, 121, 891, 7155, 63351, 617463, 6590727, 76589127, 963486567, 13052781927, 189537379047, 2937560365287, 48409889869287, 845393769958887, 15596602532173287, 303139660882458087, 6191620542649779687
(list; graph; listen)
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OFFSET
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0,4
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COMMENT
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a(n) = number of cycles that cannot be written in the form (j,j+1,j+2,...), in all permutations of {1,2,...,n}. Example: a(3)=2 because in (1)(2)(3), (1)(23), (12)(3), (13)(2), (123), (132) we have 0+0+0+1+0+1=2 such cycles.
a(n)=A000254(n) - A007489(n).
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MAPLE
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a := proc (n) options operator, arrow: factorial(n)*harmonic(n)-add(factorial(j), j = 1 .. n) end proc: seq(a(n), n = 0 .. 22);
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CROSSREFS
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A000254, A007489
Sequence in context: A037628 A037754 A037642 this_sequence A097716 A073510 A007354
Adjacent sequences: A161125 A161126 A161127 this_sequence A161129 A161130 A161131
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KEYWORD
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nonn
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), Jul 14 2009
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