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A058408 Number of 3 X n nonnegative integer matrices with all column sums 4, up to row and column permutation. 2
1, 4, 26, 129, 546, 2010, 6615, 19650, 53790, 137035, 328262, 745078, 1613072, 3348198, 6693822, 12937656, 24253200, 44219610, 78604130, 136511100, 232054284 (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

Table of n, a(n) for n=0..20.

Number of m x l nonnegative integer matrices with all column sums equal to n, up to row and column permutation

FORMULA

G.f.: 1/6*(1/(1-x)^15+3/(1-x)^3/(1-x^2)^6+2/(1-x^3)^5).

CROSSREFS

Cf. A050531, A058389, A058407.

Sequence in context: A245460 A261738 A184263 * A053906 A316539 A197964

Adjacent sequences:  A058405 A058406 A058407 * A058409 A058410 A058411

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Nov 25 2000

STATUS

approved

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Last modified February 16 21:46 EST 2020. Contains 331975 sequences. (Running on oeis4.)