%I #18 Oct 14 2024 11:25:06

%S 1,4,16,340,89520,290838284,12092687195284,6675338514190905402,

%T 50327836869668591230004816,5292118931181847999077738163123240,

%U 7888144623867099277720906683959732404332016,168815361056027801755263418243053345902341535059333028

%N Number of n X n 0..3 matrices with all row and column sums equal.

%e Some solutions for n=3

%e ..2..1..1....1..3..1....0..2..1....2..2..2....0..0..3....1..2..1....1..3..3

%e ..0..1..3....1..1..3....3..0..0....2..2..2....2..1..0....0..1..3....3..1..3

%e ..2..2..0....3..1..1....0..1..2....2..2..2....1..2..0....3..1..0....3..3..1

%Y Column k=3 of A202784.

%K nonn,changed

%O 0,2

%A _R. H. Hardin_, Feb 20 2002

%E Added one term and example - _R. H. Hardin_, Jan 05, 2012

%E a(7)-a(10) from _Andrew Howroyd_, Jun 01 2017

%E a(11) from _Sean A. Irvine_, Dec 14 2023

%E a(0)=1 prepended by _Andrew Howroyd_, Oct 14 2024