162855

Appears in sequences

• Number of symmetric difference-closed 4-sets consisting of sets consisting of an even number of pairwise disjoint 2-subsets of {1,2,...,n}.at n=10A266503
• a(n) = lcm(1,2,...,n) * Sum_{k=1..n} (2^(k-1) - 1) / k.at n=8A331343