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Search: id:A066991
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| A066991 |
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Square array read by antidiagonals of number of ways of dividing nk labeled items into k unlabeled orders with n items in each order. |
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+0
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| 1, 1, 2, 1, 12, 6, 1, 120, 360, 24, 1, 1680, 60480, 20160, 120, 1, 30240, 19958400, 79833600, 1814400, 720, 1, 665280, 10897286400, 871782912000, 217945728000, 239500800, 5040, 1, 17297280, 8892185702400, 20274183401472000
(list; table; graph; listen)
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OFFSET
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1,3
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COMMENT
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T(p,k)=(pk)!/k! is divisible by p^k but not p^(k+1) for p prime; e.g. T(3,4)=3^4*11*10*8*7*5*4*2*1=19958400.
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FORMULA
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T(n, k)=(nk)!/k!
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EXAMPLE
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Rows start: 1,1,1,1,...; 2,12,120,1680,...; 6,360,60480,19958400,...; 24,20160,79833600,871782912000,...
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CROSSREFS
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Rows include A000012, A001813, A064350. Columns include A000142, A002674, A065961. Cf. A060538, A060539, A060540.
Sequence in context: A049055 A008285 A119274 this_sequence A132875 A050139 A010255
Adjacent sequences: A066988 A066989 A066990 this_sequence A066992 A066993 A066994
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KEYWORD
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nonn,tabl
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AUTHOR
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Henry Bottomley (se16(AT)btinternet.com), Feb 01 2002
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