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A093423 Consider the triangle whose first part is shown as an example in the entry A093422. If the n-th term of the triangle read by rows is a fraction then a(n) is the denominator of the fraction, otherwise a(n)=1. 3
1, 1, 3, 1, 5, 1, 1, 7, 3, 5, 1, 9, 1, 7, 1, 1, 11, 1, 1, 1, 7, 1, 13, 3, 11, 5, 3, 1, 1, 15, 1, 13, 1, 11, 1, 1, 1, 17, 1, 5, 1, 13, 1, 11, 1, 1, 19, 3, 17, 1, 1, 7, 13, 1, 11, 1, 21, 1, 19, 1, 17, 1, 1, 1, 13, 1, 1, 23, 1, 7, 5, 19, 1, 17, 1, 1, 1, 13 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..78.

FORMULA

A093422(n,m)/A093423(n,m) = 2*binomial(n,m)*(m-1)!/(2*n-m+1) for 2<=m<n. A093422(n,1)/A093423(n,1)= n. - R. J. Mathar, Apr 28 2007

MAPLE

A09342x := proc(n, m) local a, i, N, D ; N := n ; if m = 1 then D := 1 ; else D := n ; end ; for i from 1 to m-1 do N := N*(n-i) ; D := D+n-i ; od ; simplify(N/D) ; end: A093423 := proc(n, m) denom(A09342x(n, m)) ; end: for n from 1 to 12 do for m from 1 to n do printf("%d, ", A093423(n, m)) ; od ; od ; # R. J. Mathar, Apr 28 2007

CROSSREFS

Cf. A093412, A093413, A093414, A093415, A093417, A093418, A093419, A093420, A093421, A093422.

Sequence in context: A187367 A002945 A171232 * A227507 A134700 A085407

Adjacent sequences:  A093420 A093421 A093422 * A093424 A093425 A093426

KEYWORD

nonn,tabl,frac

AUTHOR

Amarnath Murthy, Mar 30 2004

EXTENSIONS

More terms from R. J. Mathar, Apr 28 2007

Better definition from Omar E. Pol, Jan 10 2009

STATUS

approved

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Last modified September 23 17:50 EDT 2017. Contains 292363 sequences.