The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A004731 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A004731

Denominator of n!!/(n+1)!! (cf. A006882).
(history; published version)

#48 by Alois P. Heinz at Fri Sep 23 16:17:13 EDT 2022

STATUS

proposed

approved

#47 by Jon E. Schoenfield at Fri Sep 23 16:02:30 EDT 2022

STATUS

editing

proposed

#46 by Jon E. Schoenfield at Fri Sep 23 16:02:24 EDT 2022

COMMENTS

Also rational part of numerator of GAMMAGamma(n/2+1)/GAMMAGamma(n/2+1/2) (cf. A036039).

EXAMPLE

The sequence GAMMAGamma(n/2+1)/GAMMAGamma(n/2+1/2), n >= 0, begins 1/Pi^(1/2), 1/2*Pi^(1/2), 2/Pi^(1/2), 3/4*Pi^(1/2), 8/3/Pi^(1/2), 15/16*Pi^(1/2), 16/5/Pi^(1/2), ...

STATUS

approved

editing

#45 by Jon E. Schoenfield at Mon Jan 31 01:31:27 EST 2022

STATUS

editing

approved

#44 by Jon E. Schoenfield at Mon Jan 31 01:31:25 EST 2022

AUTHOR

N. J. A. Sloane.

STATUS

approved

editing

#43 by Alois P. Heinz at Sat Apr 03 15:41:42 EDT 2021

STATUS

proposed

approved

#42 by Chai Wah Wu at Sat Apr 03 14:58:05 EDT 2021

STATUS

editing

proposed

#41 by Chai Wah Wu at Sat Apr 03 14:58:00 EDT 2021

PROG

return b//gcd(a, b) # Chai Wah Wu, Apr 03 2021

#40 by Chai Wah Wu at Sat Apr 03 14:57:47 EDT 2021

PROG

(Python)

from sympy import gcd, factorial2

def A004731(n):

if n <= 1:

return 1

a, b = factorial2(n-2), factorial2(n-1)

return b//gcd(a, b) # Chai Wah Wu, Apr 03 2021

STATUS

approved

editing

#39 by Joerg Arndt at Sat Aug 15 08:48:20 EDT 2020

STATUS

reviewed

approved