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Search: id:A006321
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| A006321 |
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Royal paths in a lattice.
(Formerly M4535)
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+0
4
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| 1, 8, 48, 264, 1408, 7432, 39152, 206600, 1093760, 5813000, 31019568, 166188552, 893763840, 4823997960, 26124870640, 141926904328, 773293020928, 4224773978632
(list; graph; listen)
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OFFSET
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0,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
G. Kreweras, Sur les hi\'{e}rarchies de segments, Cahiers Bureau Universitaire Recherche Op\'{e}rationnelle, Cahier 20, Inst. Statistiques, Univ. Paris, 1973.
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FORMULA
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a(n)=(4/n)*sum(binomial(n, j)*binomial(n+3+j, n-1), j=0..n) (n>0). - Emeric Deutsch (deutsch(AT)duke.poly.edu), Aug 19 2004
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MAPLE
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1, seq(4*sum(binomial(n, j)*binomial(n+3+j, n-1), j=0..n)/n, n=1..17);
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CROSSREFS
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Fourth diagonal of A033877
Sequence in context: A026761 A026706 A128734 this_sequence A081554 A079743 A079765
Adjacent sequences: A006318 A006319 A006320 this_sequence A006322 A006323 A006324
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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