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 A108576 Number of 3 X 3 magic squares (with distinct positive entries) having all entries < n. 8
 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 16, 40, 64, 96, 128, 184, 240, 320, 400, 504, 608, 744, 880, 1056, 1232, 1440, 1648, 1904, 2160, 2464, 2768, 3120, 3472, 3880, 4288, 4760, 5232, 5760, 6288, 6888, 7488, 8160, 8832, 9576, 10320, 11144, 11968, 12880, 13792, 14784, 15776 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,10 COMMENTS From Thomas Zaslavsky, Mar 12 2010: (Start) A magic square has distinct positive integers in its cells, whose sum is the same (the "magic sum") along any row, column, or main diagonal. a(n) is given by a quasipolynomial of period 12. (End) LINKS T. Zaslavsky, Table of n, a(n) for n = 1..10000. M. Beck and T. Zaslavsky, An enumerative geometry for magic and magilatin labellings, arXiv:math/0506315 [math.CO], 2005; Ann. Combinatorics, 10 (2006), no. 4, 395-413. MR 2007m:05010. Zbl 1116.05071. - Thomas Zaslavsky, Jan 29 2010 M. Beck and T. Zaslavsky, Six little squares and how their numbers grow, submitted. - Thomas Zaslavsky, Jan 29 2010 Matthias Beck and Thomas Zaslavsky, Six Little Squares and How their Numbers Grow, Journal of Integer Sequences, 13 (2010), Article 10.6.2. Index entries for linear recurrences with constant coefficients, signature (2,-1,0,1,-2,2,-2,1,0,-1,2,-1). FORMULA G.f.: (8*x^10*(2*x^2+1)) / ((1-x^6)*(1-x^4)*(1-x)^2). a(n) is given by a quasipolynomial of period 12. EXAMPLE a(10) = 8 because there are 8 3 X 3 magic squares with distinct entries < 10 (they are the standard magic squares). MATHEMATICA LinearRecurrence[{2, -1, 0, 1, -2, 2, -2, 1, 0, -1, 2, -1}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 16, 40}, 60] (* Jean-François Alcover, Nov 12 2018 *) CoefficientList[Series[(8 x^10 (2 x^2 + 1)) / ((1 - x^6) (1 - x^4) (1 - x)^2), {x, 0, 60}], x] (* Vincenzo Librandi, Nov 12 2018 *) PROG (PARI) a(n)=1/6*(n^3-16*n^2+(76-3*(n%2))*n -[96, 58, 96, 102, 112, 90, 96, 70, 96, 90, 112, 102][(n%12)+1]) CROSSREFS Cf. A108577, A108578, A108579. Sequence in context: A156331 A269513 A024700 * A052207 A038578 A155110 Adjacent sequences:  A108573 A108574 A108575 * A108577 A108578 A108579 KEYWORD nonn,easy AUTHOR Thomas Zaslavsky and Ralf Stephan, Jun 11 2005 EXTENSIONS Edited by N. J. A. Sloane, Feb 05 2010 STATUS approved

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Last modified October 21 16:25 EDT 2019. Contains 328302 sequences. (Running on oeis4.)