39843

Appears in sequences

• Number of unrooted achiral trees with n nodes.at n=43A003244
• Number of nX1 0..2 arrays with values 0..2 introduced in row major order, the number of instances of each value within one of each other, and every element equal to one or two horizontal or vertical neighbors.at n=22A199034
• a(n) is the number of 5 element sets of distinct integer-sided trapezoids whose base angles are 60 degrees that fill an equilateral triangular grid of side n units formed by directly binary space partitioning 3-trapezoid sets without forming 4-trapezoid sets.at n=44A391203