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 A007045 Second diagonal of partition triangle A047812. (Formerly M3896) 1
 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; graph; refs; listen; history; text; internal format)
 OFFSET 2,3 REFERENCES 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). LINKS MATHEMATICA 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 *) CROSSREFS Sequence in context: A062158 A034133 A006504 * A102227 A173034 A006010 Adjacent sequences:  A007042 A007043 A007044 * A007046 A007047 A007048 KEYWORD nonn,nice AUTHOR N. J. A. Sloane, R. K. Guy STATUS approved

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