900368

Appears in sequences

• Number of Ferrers diagrams with a single Ferrers puncture with the same orientation inscribed strictly inside with half-perimeter = n.at n=11A133106
• a(n) is the number of ways to insert single pairs of parenthesis to completely separate n identical objects in a straight line such that at least one of the objects at the two ends is not enclosed.at n=11A157418