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A120995 Denominators of rationals related to John Wallis' product formula for Pi/2 (from his 'Arithmetica infinitorum' from 1659). 2
1, 15, 175, 3675, 14553, 231231, 920205, 234652275, 2807136475, 14933966047, 59612442981, 11425718238025, 15211755050625, 243077636829375, 971230202264925, 993568496917018275, 3970836034391543625 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

The corresponding numerators are A120994.

The rationals W(n):= (((4^n)/binomial(2*n,n))^2)/(2*n+1) converge to Pi/2 = 1.570796327...

LINKS

Table of n, a(n) for n=1..17.

FORMULA

a(n) = denominators((3/4)*W(n)), n>=1.

CROSSREFS

Sequence in context: A145147 A069379 A184285 * A024197 A210782 A071535

Adjacent sequences:  A120992 A120993 A120994 * A120996 A120997 A120998

KEYWORD

nonn,easy,frac

AUTHOR

Wolfdieter Lang, Aug 01 2006

STATUS

approved

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Last modified June 6 04:15 EDT 2020. Contains 334859 sequences. (Running on oeis4.)