311214domain: NAppears in sequencesNumber of (n+2)X(4+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 2 3 4 6 or 7 and every 3X3 column and antidiagonal sum not equal to 2 3 4 6 or 7.at n=7A252403Numbers k for which k and k^2 are digitally balanced numbers in base 3 (A049354).at n=21A372147