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
KEYWORD
nonn
AUTHOR
Thomas Zaslavsky, Mar 03 2010
STATUS
approved