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A129684
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Exponential Riordan array [1/(1-x^2/2), x].
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2
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1, 0, 1, 1, 0, 1, 0, 3, 0, 1, 6, 0, 6, 0, 1, 0, 30, 0, 10, 0, 1, 90, 0, 90, 0, 15, 0, 1, 0, 630, 0, 210, 0, 21, 0, 1, 2520, 0, 2520, 0, 420, 0, 28, 0, 1, 0, 22680, 0, 7560, 0, 756, 0, 36, 0, 1, 113400, 0, 113400, 0, 18900, 0, 1260, 0, 45, 0, 1
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,8
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COMMENTS
| Row sums are A087214. Inverse is A129685.
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FORMULA
| Number triangle T(n,k)=[k<=n](n!/k!)*(1/2^((n-k)/2))*(1+(-1)^(n-k))/2
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EXAMPLE
| Triangle begins
1,
0, 1,
1, 0, 1,
0, 3, 0, 1,
6, 0, 6, 0, 1,
0, 30, 0, 10, 0, 1,
90, 0, 90, 0, 15, 0, 1,
0, 630, 0, 210, 0, 21, 0, 1
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CROSSREFS
| Sequence in context: A046778 A119925 A102765 * A105147 A111924 A100485
Adjacent sequences: A129681 A129682 A129683 * A129685 A129686 A129687
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KEYWORD
| easy,nonn,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Apr 28 2007
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