A127974 Numerators in expansion of (1-x)^(-2/3).

1, 2, 5, 40, 110, 308, 2618, 7480, 21505, 559130, 1621477, 4717024, 41273960, 120646960, 353323240, 3109244512, 9133405754, 26862958100, 711868389650, 2098138411600, 6189508314220, 54821359354520, 161972198092900

Offset

0,2

Comments

Numerators of n!/A008544(n) are A127975.

The sequence is related to the triple factorial numbers, A008544. - Roger L. Bagula, Dec 20 2008

Links

G. C. Greubel, Table of n, a(n) for n = 0..1000

Formula

a(n) = denominator(n!/A008544(n))

a(n) = denominator(n!/(product_{k=0..n-1} (2+3*k))).

a(n) = -3^(floor(n/3) + floor(n/9) + floor(n/27))*Product_{k=0..n} (3*k - 1)/n!. - Roger L. Bagula, Dec 20 2008

Mathematica

Table[ -3^(Floor[n/3] + Floor[n/9] + Floor[n/27])*Product[3*k - 1, {k, 0, n}]/n!, {n, 0, 50}] (* Roger L. Bagula, Dec 20 2008 *)
Numerator[CoefficientList[Series[(1 - x)^(-2/3), {x, 0, 50}], x]] (* G. C. Greubel, May 07 2018 *)

Crossrefs

Cf. A008544, A127975.

Sequence in context: A120031 A110066 A155176 * A012801 A183910 A162035

Adjacent sequences: A127971 A127972 A127973 * A127975 A127976 A127977

Keyword

easy,nonn,frac

Author

Paul Barry, Feb 09 2007

Status

approved