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Search: id:A145840
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| A145840 |
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Number of 4-compositions of n |
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+0
1
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| 1, 4, 26, 164, 1031, 6480, 40728, 255984, 1608914, 10112368, 63558392, 399478064, 2510804924, 15780945024, 99186608832, 623409013632, 3918258753416, 24627092844352, 154786536605216, 972866430709568
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OFFSET
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1,2
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COMMENT
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A 4-composition of n is a matrix with four rows, such that each column has at least one non zero element and whose elements sum up to n
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REFERENCES
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G. Louchard, Matrix compositions: a probabilistic approach, Proceedings of GASCom and Bijective Combinatorics 2008, Bibbiena, Italy, p. 159-170.
E. Munarini, M. Poneti and S. Rinaldi, Matrix compositions, Proceedings of Formal Power Series and Algebraic Combinatorics 2006, San Diego, USA, J. Remmel, M. Zabrocki (Eds.) 445-456.
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FORMULA
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a(n+4)=8*a(n+3)-12*a(n+2)+8*a(n+1)-2*a(n); G.f.:(1-x)^4/(2(1-x)^4-1)
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CROSSREFS
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A003480
Sequence in context: A121767 A092167 A124544 this_sequence A108082 A116429 A084134
Adjacent sequences: A145837 A145838 A145839 this_sequence A145841 A145842 A145843
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KEYWORD
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nonn
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AUTHOR
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Simone Rinaldi (rinaldi(AT)unisi.it), Oct 21 2008
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