The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A189886

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A189886

a(n) is the number of compositions of the set {1, 2, ..., n} into blocks, each of size 1, 2 or 3 (n >= 0).
(history; published version)

#47 by N. J. A. Sloane at Mon Jan 30 21:24:44 EST 2017

STATUS

editing

approved

#46 by N. J. A. Sloane at Mon Jan 30 21:24:41 EST 2017

LINKS

Moa Apagodu, David Applegate, N. J. A. Sloane, and Doron Zeilberger, <a href="http://arxiv.org/abs/1701.08394">Analysis of the Gift Exchange Problem</a>, arXiv:1701.08394, 2017.

STATUS

approved

editing

#45 by Alois P. Heinz at Thu Sep 22 10:17:34 EDT 2016

STATUS

editing

approved

#44 by Alois P. Heinz at Thu Sep 22 10:17:12 EDT 2016

CROSSREFS

Column k=3 of A276921.

#43 by Alois P. Heinz at Thu Sep 22 09:57:20 EDT 2016

MAPLE

seq(a(n), n=0..2425); # Alois P. Heinz, Sep 22 2016

# third Maple program:

a:= n-> n! * (<<0|1|0>, <0|0|1>, <1/6|1/2|1>>^n)[3, 3]:

seq(a(n), n=0..25); # Alois P. Heinz, Sep 22 2016

#42 by Alois P. Heinz at Thu Sep 22 09:44:54 EDT 2016

CROSSREFS

Cf. A144422, A000670, A001680.

#41 by Alois P. Heinz at Thu Sep 22 09:43:03 EDT 2016

LINKS

Alois P. Heinz, <a href="/A189886/b189886.txt">Table of n, a(n) for n = 0..424</a>

#40 by Alois P. Heinz at Thu Sep 22 09:40:53 EDT 2016

MAPLE

# second Maple program:

a:= proc(n) option remember; `if`(n=0, 1, add(

a(n-i)*binomial(n, i), i=1..min(n, 3)))

end:

seq(a(n), n=0..24); # Alois P. Heinz, Sep 22 2016

STATUS

approved

editing

#39 by Alois P. Heinz at Wed Feb 12 21:53:38 EST 2014

STATUS

proposed

approved

#38 by Jon E. Schoenfield at Wed Feb 12 20:48:09 EST 2014

STATUS

editing

proposed