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Search: id:A068928
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| A068928 |
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Number of incongruent ways to tile a 3 X 2n room with 1x2 Tatami mats. At most 3 Tatami mats may meet at a point. |
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5
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| 2, 2, 2, 4, 5, 9, 12, 21, 30, 51, 76, 127, 195, 322, 504, 826, 1309, 2135, 3410, 5545, 8900, 14445, 23256, 37701, 60813, 98514, 159094, 257608, 416325, 673933, 1089648, 1763581, 2852242, 4615823, 7466468, 12082291, 19546175, 31628466
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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For n >= 8, a(n) = a(n-1) + 2*a(n-2) - a(n-3) - a(n-5) - a(n-6).
O.g.f.: x(2-4x^2-x^4+x^6)/((1-x-x^2)(1-x^2-x^4)). a(n) = (A000045(n+1)+A053602(n+1))/2, n>1. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 30 2008]
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CROSSREFS
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Cf. A068922 for total number of tilings, A068926 for more info.
Essentially the same as A001224.
Sequence in context: A057591 A024405 A082547 this_sequence A152968 A147599 A086420
Adjacent sequences: A068925 A068926 A068927 this_sequence A068929 A068930 A068931
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KEYWORD
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easy,nonn
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AUTHOR
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Dean Hickerson (dean.hickerson(AT)yahoo.com), Mar 11 2002
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