A284991 - OEIS

%I #18 Apr 10 2017 15:18:16

%S 1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,0,10,20,45,44,265,1920,6300,13720,

%T 20175,18000,7570,357435,2398900,7499940,14372820,18433415,15729000,

%U 8171730,1975560,749649145,4695264000,13718863480,24545693760,29544855480,24545693760,13718863480,4695264000,749649145

%N Triangle T(n,t) read by rows: the number of n X n {0,1} matrices with trace t where each row sum and each column sum is 4.

%H Alois P. Heinz, <a href="/A284991/b284991.txt">Rows n = 0..10, flattened</a>

%H <a href="/index/Mat#binmat">Index entries for sequences related to binary matrices</a>

%e 0:       1

%e 1:       0       0

%e 2:       0       0       0

%e 3:       0       0       0        0

%e 4:       0       0       0        0        1

%e 5:       1       0      10       20       45       44

%e 6:     265    1920    6300    13720    20175    18000    7570

%e 7:  357435 2398900 7499940 14372820 18433415 15729000 8171730 1975560

%Y Cf. A058528 (row sums), A007105 (diagonal?), A139670 (symmetric matrices).

%K nonn,tabl

%O 0,18

%A _R. J. Mathar_, Apr 07 2017

%E More terms from _Alois P. Heinz_, Apr 09 2017