A357140 - OEIS

%I #5 Sep 15 2022 07:53:04

%S 1,0,0,1,26,865,39268,2375965,185974145,18337523130,2227232055239,

%T 327003956573263,57121908284696448,11712143532463633752,

%U 2786114854266411595229,761208643373263480081077,236761580851204534640426709,83183218467008383189955036015

%N Number of n X n triangular (0,1)-matrices with exactly 2n entries equal to 1 and no zero rows or columns.

%F a(n) = A137252(2n,n).

%Y Cf. A137252.

%K nonn

%O 0,5

%A _Alois P. Heinz_, Sep 14 2022