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 A062801 Number of 2 X 2 non-singular integer matrices with entries from {0,...,n}. 11
 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; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS All these numbers are even because there are the same number of matrices with positive and negative determinants. [From T. D. Noe, Oct 08 2008] LINKS MATHEMATICA 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, Oct 08 2008] CROSSREFS 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: A187670 A187462 A231270 * A035290 A138422 A001303 Adjacent sequences:  A062798 A062799 A062800 * A062802 A062803 A062804 KEYWORD nonn,nice AUTHOR Ahmed Fares (ahmedfares(AT)my-deja.com), Jul 19 2001 EXTENSIONS More terms from T. D. Noe, Oct 08 2008 STATUS approved

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Last modified May 21 14:54 EDT 2019. Contains 323443 sequences. (Running on oeis4.)