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Search: id:A003019
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| A003019 |
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Number of distinct values taken by 4^4^...^4 (with n 4's and parentheses inserted in all possible ways).
(Formerly M1179)
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+0
11
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| 1, 1, 2, 4, 9, 20, 48, 114, 282, 703, 1787, 4583, 11900, 31131, 82117, 217954, 581970, 1561704, 4210263, 11396488, 30963024, 84402984, 230779071
(list; graph; listen)
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OFFSET
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1,3
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REFERENCES
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R. K. Guy and J. L. Selfridge, The nesting and roosting habits of the laddered parenthesis. Amer. Math. Monthly 80 (1973), 868-876.
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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Index entries for sequences related to parenthesizing
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CROSSREFS
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Cf. A002845, A003018, A145545, A145546, A145547, A145548, A145549, A145550, A000081.
Sequence in context: A036624 A034823 A036625 this_sequence A036626 A036722 A034824
Adjacent sequences: A003016 A003017 A003018 this_sequence A003020 A003021 A003022
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KEYWORD
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nonn,nice,more
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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a(12) - a(23) from Jon Schoenfield (jonscho(AT)hiwaay.net), Oct 11 2008
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