A054771 Number of nonnegative integer 3 X 3 matrices with sum of elements equal to n, up to rotational symmetry.

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

Offset: 0

Author

Vladeta Jovovic, May 18 2000

Keywords

• easy
• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..1000

Crossrefs

Row n=3 of A343874.

Cf. A008610, A054343.

Formula

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).