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A072973 Denominator of b(n) = (50*n-6)/C(3n,n)/2^n. 1
1, 3, 30, 14, 3960, 24024, 28288, 1860480, 94140288, 199971200, 1183311360, 12386350080, 284826214400, 2376389615616, 433030996623360, 15188999733248, 73886889202384896, 484018391833804800, 4234776786964971520 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

A powerful series to compute Pi via the Beta method. Proved first by Almkvist, Krattenthaler, Petersson (2001).

LINKS

Table of n, a(n) for n=0..18.

FORMULA

sum ( k>=0, b(k)) = Pi

PROG

(PARI) a(n)=denominator((50*n-6)/binomial(3*n, n)/2^n)

CROSSREFS

Cf. A072972.

Sequence in context: A082792 A078242 A108739 * A154054 A118219 A186681

Adjacent sequences: A072970 A072971 A072972 * A072974 A072975 A072976

KEYWORD

easy,frac,nonn

AUTHOR

Benoit Cloitre, Aug 13 2002

STATUS

approved

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Last modified March 29 12:12 EDT 2023. Contains 361599 sequences. (Running on oeis4.)