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 A093420 Triangle read by rows: T(n,k) is the numerator of f(n, k) = (Product_{i = 0..k-1} (n-i))/(Sum_{i = 1..k} i) for 1 <= k <= n. 4

%I

%S 1,2,2,3,2,1,4,4,4,12,5,20,10,12,8,6,10,20,36,48,240,7,14,35,84,168,

%T 240,180,8,56,56,168,448,960,1440,1120,9,24,84,1512,1008,2880,6480,

%U 10080,8064,10,30,120,504,2016,7200,21600,50400,80640,725760,11,110,165

%N Triangle read by rows: T(n,k) is the numerator of f(n, k) = (Product_{i = 0..k-1} (n-i))/(Sum_{i = 1..k} i) for 1 <= k <= n.

%F T(n,n) = numerator(f(n, n)) = numerator(2*(n-1)!/(n+1)) = A090586(n).

%e Triangle T(n,k) (with rows n >= 1 and columns k >= 1) begins as follows:

%e 1,

%e 2, 2,

%e 3, 2, 1,

%e 4, 4, 4, 12,

%e 5, 20, 10, 12, 8,

%e 6, 10, 20, 36, 48, 240,

%e 7, 14, 35, 84, 168, 240, 180;

%e ...

%Y Cf. A090585, A090586, A093412, A093421 (denominators), A093422.

%K nonn,easy,frac,tabl,less

%O 1,2

%A _Amarnath Murthy_, Mar 30 2004

%E Edited and extended by _David Wasserman_, Aug 29 2006

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Last modified September 30 17:12 EDT 2020. Contains 337440 sequences. (Running on oeis4.)