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Revision History for A334578 (Underlined text is an addition; strikethrough text is a deletion.)

Showing entries 1-10 | older changes
A334578 Double subfactorials: a(n) = (-1)^floor(n/2) * n!! * Sum_{i=0..floor(n/2)} (-1)^i/(n-2*i)!!.
(history; published version)
#41 by Alois P. Heinz at Fri Nov 27 07:40:15 EST 2020
STATUS

proposed

approved

#40 by Jean-François Alcover at Fri Nov 27 07:33:56 EST 2020
STATUS

editing

proposed

#39 by Jean-François Alcover at Fri Nov 27 07:33:50 EST 2020
MATHEMATICA

RecurrenceTable[{a[0] == 1, a[1] == 1, a[n] == n a[n-2] + (-1)^Floor[n/2]}, a, {n, 0, 32}] (* Jean-François Alcover, Nov 27 2020 *)

STATUS

approved

editing

#38 by N. J. A. Sloane at Sun Oct 25 22:44:58 EDT 2020
STATUS

reviewed

approved

#37 by Joerg Arndt at Sun Oct 25 10:39:16 EDT 2020
STATUS

proposed

reviewed

#36 by Michel Marcus at Sun Oct 25 07:43:01 EDT 2020
STATUS

editing

proposed

#35 by Michel Marcus at Sun Oct 25 07:42:18 EDT 2020
COMMENTS

From Ryan Brooks, Oct 25 2020: (Start)

a(2n)/A006882(2n) ~ 1/sqrt(e) = A092605.

a(2n+1)/A006882(2n+1) ~ sqrt(pi/(2*e))*erfi(1/sqrt(2)) = A306858. (End)

FORMULA

From Ryan Brooks, Oct 25 2020: (Start)

a(2n)/A006882(2n) ~ 1/sqrt(e) = A092605.

a(2n+1)/A006882(2n+1) ~ sqrt(Pi/(2*e))*erfi(1/sqrt(2)) = A306858. (End)

Discussion
Sun Oct 25 07:43
Michel Marcus: Pi rather than pi; formulas in formula section : block attribution for 2 formulas  : see stylesheet
#34 by Michel Marcus at Sun Oct 25 07:41:45 EDT 2020
COMMENTS

a(2n)/A006882(2n) ~ 1/sqrt(e) = A092605. _From _Ryan Brooks_, Oct 25 2020: (Start)

a(2n)/A006882(2n) ~ 1/sqrt(e) = A092605.

a(2n+1)/A006882(2n+1) ~ sqrt(pi/(2*e))*erfi(1/sqrt(2)) = A306858. _Ryan Brooks_, Oct 25 2020. (End)

STATUS

proposed

editing

#33 by Ryan Brooks at Sun Oct 25 07:39:04 EDT 2020
STATUS

editing

proposed

#32 by Ryan Brooks at Sun Oct 25 07:38:32 EDT 2020
COMMENTS

a(2n)/A006882(2n) ~ 1/sqrt(e) = A092605.. _Ryan Brooks_, Oct 25 2020

a(2n+1)/A006882(2n+1) ~ sqrt(pi/(2*e))*erfi(1/sqrt(2)) = A306858.. _Ryan Brooks_, Oct 25 2020

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Last modified August 29 18:55 EDT 2024. Contains 375518 sequences. (Running on oeis4.)