53198

Appears in sequences

• Let p(k) be the number of partitions of k (A000041); a(n) = Sum_{1<=k<=n, gcd(k,n)=1} p(k).at n=34A096223
• Numbers with no 1's in their base-3, base-4, and base-5 expansions. Intersection of A005823, A023709, and A023725.at n=24A117482
• a(n) = Sum_{i=0..n-1} (n+i)*a(n-1-i) for n>1, a(0)=1, a(1)=1.at n=7A193668
• E.g.f.: exp(2 * (exp(x) - 1 - x - x^2 / 2 - x^3 / 6)).at n=12A339017
• Number of fixed hexagonal polyominoes with n cells that have a horizontal axis of symmetry that is a diagonal of at least one of the n cells.at n=17A347258