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A145840
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Number of 4-compositions of n
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0
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1, 4, 26, 164, 1031, 6480, 40728, 255984, 1608914, 10112368, 63558392, 399478064, 2510804924, 15780945024, 99186608832, 623409013632, 3918258753416, 24627092844352, 154786536605216, 972866430709568
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| 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
| 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 (Editors) 445-456.
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FORMULA
| 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
| A003480
Sequence in context: A121767 A092167 A124544 * A108082 A199490 A116429
Adjacent sequences: A145837 A145838 A145839 * A145841 A145842 A145843
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KEYWORD
| nonn
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AUTHOR
| Simone Rinaldi (rinaldi(AT)unisi.it), Oct 21 2008
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