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Search: id:A006045
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| A006045 |
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Sum of orders of all 2 X 2 matrices with entries mod n.
(Formerly M3946)
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+0
2
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OFFSET
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1,2
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COMMENT
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The order of a matrix M over Z/(nZ) is the smallest k such that M^k is idempotent.
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Wilansky, Albert; Spectral decomposition of matrices for high school students. Math. Mag. 41 1968 51-59.
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CROSSREFS
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Adjacent sequences: A006042 A006043 A006044 this_sequence A006046 A006047 A006048
Sequence in context: A059744 A016106 A092723 this_sequence A137787 A022686 A130901
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Albert Wilansky
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EXTENSIONS
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The article gives an incorrect value for a(5).
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