66004

Appears in sequences

• Row 4 of array in A047666.at n=20A047668
• Sum over all subsets of {1,..,n} of the GCD of the subset.at n=15A065568
• Irregular table read by rows: Take a diagonal-edged (or diamond-shaped) checkerboard with all diagonals drawn, as in A333434. Then T(n,k) = number of k-sided polygons in that figure for k >= 3.at n=31A333458