191910

Appears in sequences

• a(n) is the least number not occurring earlier such that neighboring digits sum to 1 or 10.at n=30A182396
• Number of (n+2)X(5+2) 0..3 arrays with every consecutive three elements in every row and column not having exactly two distinct values, and in every diagonal and antidiagonal having exactly two distinct values, and new values 0 upwards introduced in row major order.at n=27A253022