33235358domain: NAppears in sequencesNumber of (3*n)Xn binary matrices with all row sums equal and all column sums equal.at n=3A181235T(n,k)=Number of (k*n)Xn binary matrices with all row sums equal and all column sums equal.at n=18A181236Number of (4*n)X4 binary matrices with all row sums equal and all column sums equal.at n=2A181238