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A054771
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Number of nonnegative integer 3 X 3 matrices with sum of elements equal to n, up to rotational symmetry.
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2
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1, 3, 13, 43, 129, 327, 761, 1619, 3238, 6098, 10974, 18930, 31550, 50930, 80030, 122666, 183999, 270525, 390755, 555205, 777287, 1073297, 1463583, 1972533, 2630044, 3471508, 4539660, 5884564, 7565868, 9652788, 12226860, 15381924
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OFFSET
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0,2
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LINKS
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FORMULA
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G.f.: (x^8 - 2*x^7 + 6*x^6 + 2*x^5 + 2*x^4 + 2*x^3 + 6*x^2 - 2*x + 1)/((1 - x^4)^2*(1 - x^2)^2*(1 - x)^5).
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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