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A122851
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Number triangle T(n,k)=C(k,n-k)*(n-k)!.
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1
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1, 0, 1, 0, 1, 1, 0, 0, 2, 1, 0, 0, 2, 3, 1, 0, 0, 0, 6, 4, 1, 0, 0, 0, 6, 12, 5, 1, 0, 0, 0, 0, 24, 20, 6, 1, 0, 0, 0, 0, 24, 60, 30, 7, 1, 0, 0, 0, 0, 0, 120, 120, 42, 8, 1, 0, 0, 0, 0, 0, 120, 360, 210, 56, 9, 1
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,9
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COMMENTS
| Row sums are A122852.
Triangle T(n,k), read by rows, given by (0,1,-1,0,0,1,-1,0,0,1,-1,0,0,1,...) DELTA (1,0,0,-1,2,0,0,-2,3,0,0,-3,4,...) where DELTA is the operator defined in A084938. - DELEHAM Philippe, Dec 12 2011
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FORMULA
| Number triangle T(n,k)=[k<=n]*k!/(2k-n)!
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EXAMPLE
| Triangle begins
1,
0, 1,
0, 1, 1,
0, 0, 2, 1,
0, 0, 2, 3, 1,
0, 0, 0, 6, 4, 1,
0, 0, 0, 6, 12, 5, 1,
0, 0, 0, 0, 24, 20, 6, 1
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CROSSREFS
| Cf. A094587.
Sequence in context: A191400 A168315 A120730 * A064301 A199881 A060701
Adjacent sequences: A122848 A122849 A122850 * A122852 A122853 A122854
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KEYWORD
| easy,nonn,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Sep 14 2006
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