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Search: id:A018933
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| A018933 |
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From the game of Mousetrap. |
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+0
1
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| 2, 11, 50, 348, 2712, 23520, 225360, 2368800, 27135360, 336752640, 4503340800, 64585382400, 989138304000, 16115529830400, 278360283801600, 5081622594048000, 97772197146624000, 1977622100213760000
(list; graph; listen)
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OFFSET
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0,1
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REFERENCES
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Mundfrom, Daniel J.; A problem in permutations: the game of `Mousetrap'. European J. Combin. 15 (1994), no. 6, 555-560.
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MAPLE
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c := proc(n, x) local a, i; if n > x+1 then a := (n-2)! ; for i from 3 to x do a := a+(-1)^i*(binomial(x-2, i-2)+binomial(x-3, i-3))*(n-i)! ; od: fi; a ; end: A018933 := proc(n) if n = 5 then 2 ; elif n = 6 then 11 ; else c(n, 5) ; fi: end: for n from 5 to 23 do printf("%d, ", A018933(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 02 2008]
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CROSSREFS
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Cf. A002468.
Sequence in context: A108851 A105486 A137960 this_sequence A116586 A119366 A034574
Adjacent sequences: A018930 A018931 A018932 this_sequence A018934 A018935 A018936
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KEYWORD
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nonn
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AUTHOR
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njas
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EXTENSIONS
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This entry was corrupted by a misplaced edit Nov 30 2007; previous (and correct) version restored by njas Jan 25 2008
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 02 2008
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