A100621 - OEIS

A100621

Denominator of Cotesian number C(n,0).

1, 2, 6, 8, 90, 288, 840, 17280, 28350, 89600, 598752, 17418240, 63063000, 402361344000, 5003856000, 295206912, 976924698750, 342372925440000, 15209113920000, 5377993912811520000, 96852084769440, 89903156428800000, 37556196837868800000, 73570956727261593600000

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OFFSET

0,2

REFERENCES

Charles Jordan, Calculus of Finite Differences, Chelsea 1965, p. 513.

See A002176 for further references.

LINKS

Table of n, a(n) for n=0..23.

EXAMPLE

0, 1/2, 1/6, 1/8, 7/90, 19/288, 41/840, 751/17280, 989/28350, 2857/89600, 16067/598752, 434293/17418240, 1364651/63063000, 8181904909/402361344000, ... = A100620/A100621 = A002177/A002176 (the latter is not in lowest terms)

MATHEMATICA

cn[n_, 0] := Sum[n^j*StirlingS1[n, j]/(j + 1), {j, 1, n + 1}]/n!; cn[n_, n_] := cn[n, 0]; cn[n_, k_] := 1/n!*Binomial[n, k]*Sum[n^(j + m)*StirlingS1[k, j]*StirlingS1[n - k, m]/((m + 1)*Binomial[j + m + 1, m + 1]), {m, 1, n}, {j, 1, k + 1}]; Table[cn[n, 0] // Denominator, {n, 0, 23}] (* Jean-François Alcover, Jan 16 2013 *)

CROSSREFS

Sequence in context: A075998 A361296 A007849 * A002176 A329812 A124675

Adjacent sequences: A100618 A100619 A100620 * A100622 A100623 A100624

KEYWORD

nonn,frac

AUTHOR

N. J. A. Sloane, Dec 04 2004

STATUS

approved