The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A151881 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A151881

Sum (number of cycles)^2 over all n! permutations of [1..n].
(history; published version)

#25 by Peter Luschny at Tue Jan 14 14:09:34 EST 2020

STATUS

editing

approved

#24 by Peter Luschny at Tue Jan 14 14:09:13 EST 2020

FORMULA

a(n) = Sum_{k=0..n} |Stirling1(n,k)|*k^2. - Peter Luschny, Jan 14 2020

STATUS

approved

editing

#23 by Alois P. Heinz at Wed Oct 21 07:50:38 EDT 2015

STATUS

reviewed

approved

#22 by Peter Luschny at Wed Oct 21 07:48:01 EDT 2015

STATUS

proposed

reviewed

#21 by Peter Luschny at Wed Oct 21 07:47:58 EDT 2015

STATUS

editing

proposed

#20 by Peter Luschny at Wed Oct 21 07:47:53 EDT 2015

MAPLE

# Alternatively after Reshetnikov:

a := n -> n!*(add(1/k, k=1..n)^2 + add(1/k-1/k^2, k=1..n)):

seq(a(n), n=1..19); # Peter Luschny, Oct 21 2015

STATUS

approved

editing

#19 by OEIS Server at Wed Oct 21 07:36:34 EDT 2015

LINKS

N. J. A. Sloane and Alois P. Heinz, <a href="/A151881/b151881_1.txt">Table of n, a(n) for n = 1..450</a> (first 30 terms from N. J. A. Sloane)

#18 by Alois P. Heinz at Wed Oct 21 07:36:34 EDT 2015

STATUS

editing

approved

Discussion

Wed Oct 21

07:36

OEIS Server: Installed new b-file as b151881.txt.  Old b-file is now b151881_1.txt.

#17 by Alois P. Heinz at Wed Oct 21 07:36:22 EDT 2015

LINKS

N. J. A. Sloane, and Alois P. Heinz, <a href="/A151881/b151881_1.txt">Table of n, a(n) for n = 1..450</a> (first 30</a> terms from N. J. A. Sloane)

FORMULA

a(n) = (-1)^(n+1)*(Stirling1(n+1,2)-2*Stirling1(n+1,3)). [_- _Vladeta Jovovic_, Jul 22 2009]

STATUS

proposed

editing

#16 by Michel Marcus at Wed Oct 21 01:33:38 EDT 2015

STATUS

editing

proposed