1797120

Appears in sequences

• Number of double-free subsets of {1, 2, ..., n}.at n=25A050291
• a(1)=1; for n > 1, a(n) = Sum_{1<=j<n, gcd(j,n)=1} a(j)*a(n-j).at n=15A096421
• Product of the quadratic residues of prime(n).at n=6A177860
• Number of nX3 0..2 arrays with no element equal to the same number of vertical neighbors as horizontal neighbors, with new values 0..2 introduced in row major order.at n=8A241134
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 437", based on the 5-celled von Neumann neighborhood.at n=20A282217
• Number of elements of order n in the Tits group TF4(2)'.at n=9A284952
• Products of nonprimitive roots of n, or 0 if n = 2 or has no primitive roots.at n=16A347946
• a(n) is the product of the distinct nonzero quadratic residues of n.at n=16A372651