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Search: id:A062801
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| A062801 |
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Number of 2 X 2 non-singular integer matrices with entries from {0,...,n}. |
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+0
7
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| 0, 6, 50, 192, 512, 1126, 2146, 3760, 6112, 9430, 13922, 19888, 27504, 37206, 49202, 63872, 81600, 102854, 127874, 157328, 191440, 230870, 276114, 327776, 386128, 452118, 526178, 608960, 701056, 803430, 916290, 1040976, 1177744, 1327606
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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All these numbers are even because there are the same number of matrices with positive and negative determinants. [From T. D. Noe (noe(AT)sspectra.com), Oct 08 2008]
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MATHEMATICA
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Table[cnt=0; Do[If[a*d-b*c != 0, cnt++ ], {a, 0, n}, {b, 0, n}, {c, 0, n}, {d, 0, n}]; cnt, {n, 0, 10}] [From T. D. Noe (noe(AT)sspectra.com), Oct 08 2008]
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CROSSREFS
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This sequence a(n) and A059306 give together all the 2 X 2 matrices with entries from {0, ..., n}, i.e. a(n) + A059306(n) = (n+1)^4.
Sequence in context: A008786 A046195 A024268 this_sequence A035290 A138422 A001303
Adjacent sequences: A062798 A062799 A062800 this_sequence A062802 A062803 A062804
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KEYWORD
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nonn,nice
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AUTHOR
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Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 19 2001
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EXTENSIONS
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More terms from T. D. Noe (noe(AT)sspectra.com), Oct 08 2008
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