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 A107867 Triangle, read by rows, where T(n,k) = C(n*(n-1)/2-k*(k-1)/2+n-k+1,n-k). 12
 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; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Remarkably, the following matrix products are all equal to A107876: A107862^-1*A107867 = A107867^-1*A107870 = A107870^-1*A107873. LINKS EXAMPLE 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; ... PROG (PARI) T(n, k)=binomial(n*(n-1)/2-k*(k-1)/2 +n-k+1, n-k) CROSSREFS Cf. A107862, A107864, A107865, A107867, A107870, A107876. Sequence in context: A222159 A221623 A096334 * A158442 A252095 A120435 Adjacent sequences:  A107864 A107865 A107866 * A107868 A107869 A107870 KEYWORD nonn,tabl AUTHOR Paul D. Hanna, Jun 04 2005 STATUS approved

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Last modified December 5 17:42 EST 2019. Contains 329768 sequences. (Running on oeis4.)