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Search: id:A003409
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| A003409 |
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3C(2n-1,n).
(Formerly M2814)
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+0
3
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| 3, 9, 30, 105, 378, 1386, 5148, 19305, 72930, 277134, 1058148, 4056234, 15600900, 60174900, 232676280, 901620585, 3500409330, 13612702950, 53017895700, 206769793230
(list; graph; listen)
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OFFSET
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1,1
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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).
C. Domb and A. J. Barrett, Enumeration of ladder graphs, Discrete Math. 9 (1974), 341-358.
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CROSSREFS
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Equals 3 * A001700.
Sequence in context: A119372 A145268 A148956 this_sequence A029651 A148957 A148958
Adjacent sequences: A003406 A003407 A003408 this_sequence A003410 A003411 A003412
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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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