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A040175
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a(n) = n! times probability that an ordered pair of elements of S_n chosen at random (with replacement) generate S_n.
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5
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3, 9, 57, 318, 3090, 24666, 234879, 2381481, 26777922, 324421053, 4265966685
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OFFSET
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3,1
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COMMENTS
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Note that a(2)=3/2 is not integer.
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REFERENCES
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J. D. Dixon, Problem 923 (BCC20.17), Indecomposable permutations and transitive groups, in Research Problems from the 20th British Combinatorial Conference, Discrete Math., 308 (2008), 621-630.
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LINKS
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FORMULA
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EXAMPLE
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Probabilities for n=1,2,3,... are 1, 3/4, 1/2, 3/8, 19/40, ...
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CROSSREFS
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KEYWORD
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nonn,more,nice
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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