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A128413
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Inverse of number triangle A128412.
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3
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1, 2, 1, 12, 8, 1, 80, 60, 12, 1, 560, 448, 112, 16, 1, 4032, 3360, 960, 180, 20, 1, 29568, 25344, 7920, 1760, 264, 24, 1, 219648, 192192, 64064, 16016, 2912, 364, 28, 1, 1647360, 1464320, 512512, 139776, 29120, 4480, 480, 32, 1, 12446720
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| First column is A069723.
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FORMULA
| Number triangle T(n,k)=if(k=0,2^n*(C(2n,n)/2+0^n/2),2^(n-k)*C(2n,n-k)); Column k has g.f. if(k=0,4x/(sqrt(1-8x)(1-sqrt(1-8x))),(1/sqrt(1-8x))*((1-4x-sqrt(1-8x))/(8x))^k);
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EXAMPLE
| Triangle begins
1,
2, 1,
12, 8, 1,
80, 60, 12, 1,
560, 448, 112, 16, 1,
4032, 3360, 960, 180, 20, 1,
29568, 25344, 7920, 1760, 264, 24, 1,
219648, 192192, 64064, 16016, 2912, 364, 28, 1
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CROSSREFS
| Cf. A128417.
Sequence in context: A010255 A085752 A074966 * A058843 A130559 A135256
Adjacent sequences: A128410 A128411 A128412 * A128414 A128415 A128416
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KEYWORD
| easy,nonn,tabl
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Mar 02 2007
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