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A002060
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Number of partitions of a n-gon into (n-5) parts.
(Formerly M3691 N1509)
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3
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OFFSET
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7,1
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COMMENTS
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a(n) = V(r=n,k=n-5), 4th subdiagonal of the triangle of V on page 240.
It appears that V(r=15,k=10) in the Cayley table is an error, so the sequence was intended to be 4, 60, 550, 4004, 25480, 148512, 813960, 4263600, 21573816, 106234700, 511801290, 2421810300, 11289642000, 51967090560, 236635858800... - R. J. Mathar, Nov 26 2011
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REFERENCES
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N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Table of n, a(n) for n=7..15.
A. Cayley, On the partitions of a polygon, Proc. London Math. Soc., 22 (1891), 237-262 = Collected Mathematical Papers. Vols. 1-13, Cambridge Univ. Press, London, 1889-1897, Vol. 13, pp. 93ff.
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MAPLE
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V := proc(r, k)
local a , t;
a := k-1;
for t from k-2 to 1 by -1 do
a := a*(r+t)/(t+2) ;
end do:
for t from 3 to k+1 do
a := a*(r-t)/(k-t+2) ;
end do:
a ;
end proc:
A002060 := proc(n)
V(n, n-5) ;
end proc:
seq(A002060(n), n=7..25) ; # R. J. Mathar, Nov 26 2011
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CROSSREFS
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Cf. A002058, A002059
Sequence in context: A060492 A112041 A210425 * A007220 A034866 A055315
Adjacent sequences: A002057 A002058 A002059 * A002061 A002062 A002063
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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STATUS
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approved
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