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A007045
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Second diagonal of partition triangle A047812.
(Formerly M3896)
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1
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0, 1, 5, 20, 51, 112, 221, 411, 720, 1221, 2003, 3206, 5021, 7728, 11698, 17472, 25766, 37580, 54254, 77617, 110087, 154942, 216488, 300456, 414365, 568113, 774571, 1050572, 1417868, 1904641, 2547152, 3392042, 4498948, 5944158, 7824703, 10263932, 13418043, 17484554
(list;
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refs;
listen;
history;
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internal format)
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OFFSET
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2,3
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REFERENCES
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R. K. Guy, Parker's permutation problem involves the Catalan numbers, Amer. Math. Monthly 100 (1993), 287-289.
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=2..39.
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MATHEMATICA
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s[n_] := s[n] = Series[Product[(1 - q^(2*n - k))/(1 - q^(k + 1)), {k, 0, n - 1}], {q, 0, n^2}]; t[n_, k_] := SeriesCoefficient[s[n], k*(n + 1)]; A007045 = Join[{0}, Table[t[n + 3, n], {n, 0, 25}] ] (* From Jean-François Alcover, Apr 25 2012 *)
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CROSSREFS
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Sequence in context: A062158 A034133 A006504 * A102227 A173034 A006010
Adjacent sequences: A007042 A007043 A007044 * A007046 A007047 A007048
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KEYWORD
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nonn,nice
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AUTHOR
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N. J. A. Sloane, R. K. Guy
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STATUS
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approved
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