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A285021 Denominator of binomial(2*n,n)/20^n. 2
1, 10, 200, 400, 16000, 800000, 16000000, 160000000, 2560000000, 25600000000, 2560000000000, 25600000000000, 1024000000000000, 409600000000000, 8192000000000000, 409600000000000000, 65536000000000000000, 655360000000000000000, 2621440000000000000000, 26214400000000000000000, 5242880000000000000000000, 52428800000000000000000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Chai Wah Wu, Table of n, a(n) for n = 0..769

FORMULA

A285020(n)/a(n) = (-1/5)^n*sqrt(Pi)/(Gamma(1/2 - n)*Gamma(1 + n)).

Sum_{k>=0} A285020(k)/a(k) = sqrt(5)/2.

Sum_{k>=0} (-1)^k*A285020(k)/a(k) = sqrt(5/6).

Sum_{k>=0} (-1)^(k+1)*A285020(k)/a(k) = -sqrt(5/6).

MAPLE

P:=proc(q)  denom((-1/5)^q*sqrt(Pi)/(GAMMA(1/2-q)*GAMMA(1+q))); end:

seq(P(i), i=0..20); # Paolo P. Lava, Apr 10 2017

MATHEMATICA

Denominator[Table[(-1/5)^n*Sqrt[Pi]/(Gamma[1/2-n]*Gamma[1+n]), {n, 0, 25}]]

CROSSREFS

Cf. A285020 (numerators).

Sequence in context: A211419 A001085 A079436 * A126431 A202436 A320671

Adjacent sequences:  A285018 A285019 A285020 * A285022 A285023 A285024

KEYWORD

nonn,frac

AUTHOR

Ralf Steiner, Apr 08 2017

STATUS

approved

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Last modified October 20 18:08 EDT 2018. Contains 316401 sequences. (Running on oeis4.)