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Search: id:A094291
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| A094291 |
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a(n) = maximal value of C(i, j) * C(n-j, n-i) for 0 <= j <= i <= n. |
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4
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| 1, 2, 4, 9, 18, 40, 100, 225, 525, 1225, 3136, 7056, 17640, 44100, 108900, 261360, 637065, 1656369, 4008004, 10020010, 25050025, 64128064, 155739584, 393853824, 1012766976, 2538950544, 6347376360, 15868440900, 41408180100, 102252852900
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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This is the number of longest common subsequences between two binary strings of the form 00...011...1.
This is a lower bound for A094837, equivalent to choosing first string (x "a"s followed by (n-x) "b"s) and second string (y "a"s followed by (n-y) "b"s)
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EXAMPLE
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a(3) is maximal with x=1, y=2, giving a(3) = C(2,1) * C(3-1,3-2). This is equivalent to the number of instances of length-2 common subsequencs between "aab" and "abb"
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CROSSREFS
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Cf. A094858-A094862, A094837, A094824, A094349, A094350.
Sequence in context: A036610 A038044 A026732 this_sequence A026765 A032175 A000678
Adjacent sequences: A094288 A094289 A094290 this_sequence A094292 A094293 A094294
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KEYWORD
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nonn
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AUTHOR
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Hugo van der Sanden (hv(AT)crypt.org), Jun 15 2004
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