262661domain: NAppears in sequencesNumbers that are the sum of 7 positive 9th powers.at n=37A003396Number of (2+2)X(n+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3X3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=21A252386