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A333890 Number of non-isomorphic n X n nonnegative integer symmetric matrices with all row and column sums equal to 5 up to permutations of rows and columns. 1
1, 1, 3, 13, 74, 556, 5369, 64000, 917235, 15450781, 300882997, 6682784998, 167423745058, 4687321410460, 145487540598936, 4972006889998672, 185965612590706251, 7572297055379416985, 334097417273761302271, 15905277840810391655517, 813931037149014145154401 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

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

FORMULA

The a(2) = 3 matrices are:

  [0 5]  [1 4]  [2 3]

  [5 0]  [4 1]  [3 2]

CROSSREFS

Column k=5 of A333737.

Sequence in context: A020094 A189886 A343787 * A009382 A110193 A038762

Adjacent sequences:  A333887 A333888 A333889 * A333891 A333892 A333893

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Apr 08 2020

STATUS

approved

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Last modified May 21 05:37 EDT 2022. Contains 353889 sequences. (Running on oeis4.)