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A333739
Number of n X n nonnegative integer symmetric matrices with all row and column sums equal to n.
1
1, 1, 3, 23, 641, 62781, 22393101, 29445929253, 144413237202513, 2664174112921403401, 186127457781265060985293, 49509854244685925218197355989, 50364892612276937755557718571828543, 196663809308382999799947201118326883990475
OFFSET
0,3
CROSSREFS
Main diagonal of A188403.
Sequence in context: A127900 A229266 A143985 * A119669 A013391 A013389
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 08 2020
STATUS
approved