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Search: id:A034182
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| A034182 |
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Not necessarily symmetric n x 2 crossword puzzle grids. |
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+0
15
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| 1, 5, 15, 39, 97, 237, 575, 1391, 3361, 8117, 19599, 47319, 114241, 275805, 665855, 1607519, 3880897, 9369317, 22619535, 54608391, 131836321, 318281037, 768398399, 1855077839, 4478554081, 10812186005, 26102926095, 63018038199
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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n X 2 binary arrays with a path of adjacent 1's and no path of adjacent 0's from top row to bottom row. - Ron Hardin (rhh(AT)cadence.com), Mar 21 2002
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FORMULA
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a(n) = 2a(n-1)+a(n-2)+4
a(n)=-2+(3/2)*[1+sqrt(2)]^(n-1)-sqrt(2)*[1-sqrt(2)]^(n-1)+(3/2)*[1-sqrt(2)]^(n-1)+[1+sqrt(2)]^(n-1) *sqrt(2), with n>=1 - Paolo P. Lava (ppl(AT)spl.at), Jun 10 2008
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CROSSREFS
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Sequence in context: A062487 A084447 A099035 this_sequence A132985 A022570 A000333
Adjacent sequences: A034179 A034180 A034181 this_sequence A034183 A034184 A034185
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KEYWORD
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nonn
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AUTHOR
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Erich Friedman (erich.friedman(AT)stetson.edu)
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