200418

Appears in sequences

• Number of permutations of length n which avoid the patterns 1234, 2431, 3421.at n=21A116834
• Number of (n+1) X (7+1) 0..1 arrays with every 2 X 2 subblock diagonal minimum minus antidiagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal maximum nondecreasing vertically.at n=10A253230