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A163869 Binomial transform of the beta numbers 1/beta(n+1,n+1) (A002457). 2
1, 7, 43, 249, 1395, 7653, 41381, 221399, 1175027, 6196725, 32512401, 169863147, 884318973, 4589954619, 23761814955, 122735222505, 632698778835, 3255832730565, 16728131746145, 85826852897675 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Also a(n) = sum {i=0..n} binomial(n,n-i) (2*i+1)$ where i$ denotes the swinging factorial of i (A056040).

REFERENCES

Peter Luschny, "Divide, swing and conquer the factorial and the lcm{1,2,...,n}", preprint, April 2008.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..300

Peter Luschny, Swinging Factorial.

FORMULA

From Vaclav Kotesovec, Oct 21 2012: (Start)

G.f.: -sqrt(x-1)/(5*x-1)^(3/2)

Recurrence: n*a(n) = (6*n+1)*a(n-1) - 5*(n-1)*a(n-2)

a(n) ~ 4*5^(n-1/2)*sqrt(n)/sqrt(Pi)

(End)

a(n) = hypergeom([3/2, -n], [1], -4) = hypergeom([3/2, n+1], [1], 4/5)/(5*sqrt(5)). - Vladimir Reshetnikov, Apr 25 2016

MAPLE

a := proc(n) local i; add(binomial(n, i)/Beta(i+1, i+1), i=0..n) end:

MATHEMATICA

CoefficientList[Series[-Sqrt[x-1]/(5*x-1)^(3/2), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 21 2012 *)

sf[n_] := With[{f = Floor[n/2]}, Pochhammer[f+1, n-f]/f!]; a[n_] := Sum[ Binomial[n, n-i]*sf[2*i+1], {i, 0, n}]; Table[a[n], {n, 0, 19}] (* Jean-Fran├žois Alcover, Jul 26 2013 *)

Table[Hypergeometric2F1[3/2, -n, 1, -4], {n, 0, 20}] (* Vladimir Reshetnikov, Apr 25 2016 *)

CROSSREFS

Cf. A163842.

Sequence in context: A081896 A193656 A125344 * A043553 A049609 A161728

Adjacent sequences:  A163866 A163867 A163868 * A163870 A163871 A163872

KEYWORD

nonn

AUTHOR

Peter Luschny, Aug 06 2009

STATUS

approved

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Last modified May 23 16:30 EDT 2017. Contains 286925 sequences.