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A119828
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Number triangle T(n,k)=(2n)!/(2k)!.
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3
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1, 2, 1, 24, 12, 1, 720, 360, 30, 1, 40320, 20160, 1680, 56, 1, 3628800, 1814400, 151200, 5040, 90, 1, 479001600, 239500800, 19958400, 665280, 11880, 132, 1, 87178291200, 43589145600, 3632428800, 121080960, 2162160, 24024, 182, 1
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Row sums are A051396(n+1). Diagonal sums are A119829. Inverse is the bi-diagonal array A119830. E.g.f. cosh(x*y)/(1-y*x^2) produces an aerated version.
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FORMULA
| Number triangle T(n,k)=[k<=n](2n)!/(2k)!
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EXAMPLE
| Triangle begins
1,
2, 1,
24, 12, 1,
720, 360, 30, 1,
40320, 20160, 1680, 56, 1,
3628800, 1814400, 151200, 5040, 90, 1
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CROSSREFS
| Sequence in context: A062763 A037943 A073876 * A101179 A184295 A013313
Adjacent sequences: A119825 A119826 A119827 * A119829 A119830 A119831
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KEYWORD
| easy,nonn,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), May 25 2006
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