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A054771 Number of nonnegative integer 3 X 3 matrices with sum of elements equal to n, up to rotational symmetry. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..31.

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).

CROSSREFS

Cf. A008610, A054343.

Sequence in context: A247584 A049173 A049156 * A258776 A201710 A019008

Adjacent sequences:  A054768 A054769 A054770 * A054772 A054773 A054774

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, May 18 2000

STATUS

approved

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Last modified October 15 11:56 EDT 2018. Contains 316230 sequences. (Running on oeis4.)