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A093421 Triangle read by rows: T(n,k) is the denominator of f(n, k) = (Product_{i = 0..k-1} (n-i))/(Sum_{i = 1..k} i) for 1 <= k <= n. 3
1, 1, 3, 1, 1, 1, 1, 1, 1, 5, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 11, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 13, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..105.

FORMULA

T(n,n) = denominator(f(n, n)) = denominator(2*(n-1)!/(n+1)).

EXAMPLE

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

  1;

  1, 3;

  1, 1, 1;

  1, 1, 1, 5;

  1, 3, 1, 1, 1;

  1, 1, 1, 1, 1, 7;

  1, 1, 1, 1, 1, 1, 1;

  1, 3, 1, 1, 1, 1, 1, 1;

  1, 1, 1, 5, 1, 1, 1, 1, 1;

  1, 1, 1, 1, 1, 1, 1, 1, 1, 11;

  ...

CROSSREFS

Cf. A090585, A090586, A093415, A093420 (numerators), A093423.

Sequence in context: A134866 A143261 A204116 * A146531 A285865 A318451

Adjacent sequences:  A093418 A093419 A093420 * A093422 A093423 A093424

KEYWORD

nonn,easy,frac,tabl,less

AUTHOR

Amarnath Murthy, Mar 30 2004

EXTENSIONS

Edited and extended by David Wasserman, Aug 29 2006

STATUS

approved

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Last modified October 1 03:36 EDT 2020. Contains 337441 sequences. (Running on oeis4.)