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Search: id:A000782
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| A000782 |
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2*Catalan(n)-Catalan(n-1). |
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+0
4
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| 1, 3, 8, 23, 70, 222, 726, 2431, 8294, 28730, 100776, 357238, 1277788, 4605980, 16715250, 61020495, 223931910, 825632610, 3056887680, 11360977650, 42368413620, 158498860260, 594636663660, 2236748680998, 8433988655580, 31872759742852, 120699748759856
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OFFSET
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1,2
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COMMENT
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a(n) = (7n-5)/(n+1) * C(n-1), where C(n) = A000108(n). - Ralf Stephan (ralf(AT)ark.in-berlin.de), Jan 13 2004
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REFERENCES
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J. R. Stembridge, Some combinatorial aspects of reduced words in finite Coxeter groups. Trans. Amer. Math. Soc. 349 (1997), no. 4, 1285-1332.
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FORMULA
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Expansion of (1+x^1*C^1)*C^2, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108.
Also, apart from initial term, expansion of (1+x^2*C^2)*C, where C = (1-(1-4*x)^(1/2))/(2*x) is g.f. for Catalan numbers, A000108.
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CROSSREFS
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Partial sums of A071735. Cf. A000108.
Essentially the same as A061557.
Sequence in context: A002712 A005960 A061557 this_sequence A127385 A080410 A124462
Adjacent sequences: A000779 A000780 A000781 this_sequence A000783 A000784 A000785
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KEYWORD
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nonn
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AUTHOR
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njas
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