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 A058407 Number of 3 X n nonnegative integer matrices with all column sums 3, up to row and column permutation. 6
 1, 3, 13, 44, 134, 356, 876, 1966, 4146, 8236, 15592, 28252, 49357, 83377, 136837, 218728, 341554, 522064, 782810, 1153180, 1671698, 2387568, 3363738, 4679208, 6433183, 8748119, 11775343, 15699188, 20744108, 27180308, 35332850, 45588746 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Number of 3 X n nonnegative integer matrices with all column sums equal to m, up to row and column permutation, is coefficient of x^n in expansion of 1 / 6 * (1 / (1 - x)^C(m + 2,2) + 3 / (1 - x)^floor((m + 2) / 2) / (1 - x^2)^(C(m + 2,2) - floor((m + 2) / 2)) / 2 + 2 / (1 - x)^(C(m + 2,2) - 3 * floor(C(m + 2,2) / 3)) / (1 - x^3)^floor(C(m + 2,2) / 3)). LINKS FORMULA G.f.: 1/6*(1/(1-x)^10+3/(1-x)^2/(1-x^2)^4+2/(1-x)/(1-x^3)^3). CROSSREFS Cf. A050531, A058389, A058408. Sequence in context: A284194 A209296 A193041 * A095863 A136520 A212416 Adjacent sequences:  A058404 A058405 A058406 * A058408 A058409 A058410 KEYWORD easy,nonn AUTHOR Vladeta Jovovic, Nov 25 2000 EXTENSIONS More terms from Max Alekseyev, Jun 21 2011 STATUS approved

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Last modified December 13 03:41 EST 2019. Contains 329968 sequences. (Running on oeis4.)