319760

Appears in sequences

• Number of (n+2)X(n+2) symmetric binary matrices without the pattern 1 1 1 vertically or horizontally.at n=3A190417
• Irregular triangle read by rows: T(n,k) is the number of n-permutations whose third-shortest cycle has length exactly k; n >= 0, 0 <= k <= max(0,n-2).at n=41A350016