1321888

Appears in sequences

• Number of permutations of [n] avoiding {4231, 3142, 1234}.at n=19A294726
• Place n equally spaced points on each side of an equilateral triangle, and join each of these points by a chord to the 2*n new points on the other two sides: sequence gives number of interior vertices in the resulting planar graph.at n=29A366484