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Search: id:A107867
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| A107867 |
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Triangle, read by rows, where T(n,k) = C(n*(n-1)/2-k*(k-1)/2+n-k+1,n-k). |
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+0
12
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| 1, 2, 1, 6, 3, 1, 35, 15, 4, 1, 330, 120, 28, 5, 1, 4368, 1365, 286, 45, 6, 1, 74613, 20349, 3876, 560, 66, 7, 1, 1560780, 376740, 65780, 8855, 969, 91, 8, 1, 38608020, 8347680, 1344904, 169911, 17550, 1540, 120, 9, 1, 1101716330, 215553195, 32224114
(list; table; graph; listen)
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OFFSET
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0,2
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COMMENT
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Remarkably, the following matrix products are all equal to A107876: A107862^-1*A107867 = A107867^-1*A107870 = A107870^-1*A107873.
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EXAMPLE
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Triangle begins:
1;
2,1;
6,3,1;
35,15,4,1;
330,120,28,5,1;
4368,1365,286,45,6,1;
74613,20349,3876,560,66,7,1;
1560780,376740,65780,8855,969,91,8,1; ...
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PROGRAM
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(PARI) T(n, k)=binomial(n*(n-1)/2-k*(k-1)/2 +n-k+1, n-k)
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CROSSREFS
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Cf. A107862, A107864, A107865, A107867, A107870, A107876.
Sequence in context: A089900 A138533 A096334 this_sequence A158442 A120435 A125901
Adjacent sequences: A107864 A107865 A107866 this_sequence A107868 A107869 A107870
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KEYWORD
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nonn,tabl
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Jun 04 2005
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