5431298domain: NAppears in sequencesIndices k such that 13 plus the k-th triangular number is a perfect square.at n=16A154144Number of (n+2) X (7+2) 0..3 arrays with every 3 X 3 subblock row and column sum not 2 3 6 or 7 and every diagonal and antidiagonal sum 2 3 6 or 7.at n=13A251893