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A232553
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Maximal values of permanent on (0,1) square matrices of order n with row and column sums 3.
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2
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6, 9, 13, 36, 54, 81, 216, 324, 486, 1296, 1944, 2916, 7776, 11664, 17496, 46656, 69984, 104976, 279936, 419904, 629856, 1679616, 2519424, 3779136, 10077696, 15116544, 22674816, 60466176, 90699264, 136048896, 362797056, 544195584, 816293376, 2176782336, 3265173504, 4897760256
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OFFSET
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3,1
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COMMENTS
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a(n) attains on subset of symmetric matrices with the main diagonal of 1's.
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LINKS
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FORMULA
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a(n) = floor(6^((n-h)/3)*(3/2)^h), where h=0,1 or 2, such that n == h (mod 3).
a(n) = 6*a(n-3) for n>5.
G.f.: x^3*(6+9*x+13*x^2+3*x^5) / (1-6*x^3).
(End)
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PROG
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(PARI) a(n) = h = n%3; floor(6^((n-h)/3)*(3/2)^h); \\ Michel Marcus, Nov 26 2013
(PARI) Vec(x^3*(6+9*x+13*x^2+3*x^5)/(1-6*x^3) + O(x^50)) \\ Colin Barker, May 27 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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