%I #4 Apr 09 2020 12:30:38
%S 1,1,3,23,641,62781,22393101,29445929253,144413237202513,
%T 2664174112921403401,186127457781265060985293,
%U 49509854244685925218197355989,50364892612276937755557718571828543,196663809308382999799947201118326883990475
%N Number of n X n nonnegative integer symmetric matrices with all row and column sums equal to n.
%Y Main diagonal of A188403.
%K nonn
%O 0,3
%A _Andrew Howroyd_, Apr 08 2020