320379domain: NAppears in sequencesNumbers k such that the period of the continued fraction for sqrt(k) contains exactly 83 ones.at n=27A031851Number of (n+2)X(1+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 2 3 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 2 3 6 or 7.at n=29A252525