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 A173727 Number of reduced 3 X 3 semimagic squares with distinct nonnegative integer entries and maximum entry n. 1
 72, 144, 432, 1008, 1512, 2592, 3672, 5328, 6696, 9648, 11736, 15552, 17856, 23760, 26712, 33840, 37872, 46512, 51408, 62784, 67824, 81360, 88128, 103680, 111096, 130320, 138384, 159840, 170136, 194400, 205416, 234144, 245448, 277488, 291816 (list; graph; refs; listen; history; text; internal format)
 OFFSET 8,1 COMMENTS In a semimagic square the row and column sums must all be equal (the "magic sum"). A reduced square has least entry 0. a(n) is given by a quasipolynomial of degree 5 and period 60. REFERENCES Matthias Beck and Thomas Zaslavsky, An enumerative geometry for magic and magilatin labellings, Annals of Combinatorics, 10 (2006), no. 4, pages 395-413. MR 2007m:05010. Zbl 1116.05071. LINKS Thomas Zaslavsky, Table of n, a(n) for n = 8..10000. Matthias Beck and Thomas Zaslavsky, Six Little Squares and How Their Numbers Grow , J. Int. Seq. 13 (2010), 10.6.2. Matthias Beck and Thomas Zaslavsky, "Six Little Squares and How their Numbers Grow" Web Site: Maple worksheets and supporting documentation. Index entries for linear recurrences with constant coefficients, signature (-2, -1, 2, 5, 5, 2, -3, -7, -7, -3, 2, 5, 5, 2, -1, -2, -1). FORMULA G.f.: 72 * { x^5/[(x-1)*(x^4-1)] + x^5/[(x-1)^2*(x^3-1)] + x^5/[(x-1)^3*(x^2-1)] + 2*x^5/[(x-1)*(x^2-1)^2) + 2*x^5/[(x^2-1)*(x^3-1)] + x^5/(x^5-1) + 2*x^6/[(x-1)*(x^2-1)*(x^3-1)] + x^6/(x^2-1)^3 + 2*x^6/[(x^2-1)*(x^4-1)] + x^6/(x^3-1)^2 + x^7/[(x^2-1)*(x^5-1)] + x^7/[(x^2-1)^2*(x^3-1)] + x^7/[(x^3-1)*(x^4-1)] + x^8/[(x^3-1)*(x^5-1)] } EXAMPLE For n=8 the cells contain 0,...,8, which have one semimagic arrangement up to symmetry. All examples are obtained by symmetries from (by rows): 0, 5, 7; 4, 6, 2; 8, 1, 3. For n=9 the cells contain all of 0,...,9 except 3 or 6, since 0 and 9 must be used; each selection has one semimagic arrangement up to symmetry. CROSSREFS Cf. A173546, A173723, A173724. A173728 counts reduced squares by magic sum. Sequence in context: A137883 A173728 A173547 * A342993 A039498 A063357 Adjacent sequences: A173724 A173725 A173726 * A173728 A173729 A173730 KEYWORD nonn AUTHOR Thomas Zaslavsky, Mar 03 2010 STATUS approved

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