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%I #11 Dec 12 2023 19:47:24
%S 1,7,49,5215,21841937,3430832678207,21070560836988719941,
%T 5258020825380244651432771257,54855616345977485934984671841940089233
%N Number of n X n 0..6 matrices with all row and column sums equal.
%e Some solutions for n=3
%e ..4..0..6....5..4..4....1..2..4....5..5..2....5..0..4....6..3..0....2..6..2
%e ..3..5..2....6..4..3....0..5..2....1..5..6....0..6..3....0..6..3....3..4..3
%e ..3..5..2....2..5..6....6..0..1....6..2..4....4..3..2....3..0..6....5..0..5
%Y Column 6 of A202784.
%K nonn,more
%O 0,2
%A _R. H. Hardin_, Feb 20 2002
%E a(0)=1 prepended and a(6)-a(7) from _Andrew Howroyd_, May 11 2020
%E a(8) from _Sean A. Irvine_, Dec 12 2023