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Search: id:A134438
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| A134438 |
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Number of tilings of a 3 X n rectangle n with "triminoes". |
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+0
1
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| 1, 1, 3, 10, 23, 62, 170, 441, 1173, 3127, 8266, 21937, 58234, 154390, 409573, 1086567, 2882021, 7645046, 20279829, 53794224, 142696606, 378522507, 1004078871, 2663452699, 7065162260, 18741269167, 49713692146, 131872134232
(list; graph; listen)
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OFFSET
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0,3
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REFERENCES
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G. Kreweras, Recouvrements d'un rectangle de largeur 3 a l'aide de triminos, Mathematiques et sciences humaines, tome 130(1995), p. 27-31.
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FORMULA
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a(n) = a(n-1)+2*a(n-2)+6*a(n-3)+a(n-4)-a(n-6)
G.f.: (1-x^3) / (1-x-2*x^2-6*x^3-x^4+x^6). [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 09 2008]
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MAPLE
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a:= n-> (Matrix([[1$2, 0$2, 1, 0]]). Matrix (6, (i, j)-> if i+1=j then 1 elif j=1 then [1, 2, 6, 1, 0, -1][i] else 0 fi)^n)[1, 2]: seq (a(n), n=0..30); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 09 2008]
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CROSSREFS
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Adjacent sequences: A134435 A134436 A134437 this_sequence A134439 A134440 A134441
Sequence in context: A145069 A080204 A115982 this_sequence A092255 A105861 A041327
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KEYWORD
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nonn
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AUTHOR
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Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jan 18 2008
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EXTENSIONS
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More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 09 2008
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