441936

Appears in sequences

• Numbers k such that the set of prime divisors of k is equal to the set of prime divisors of sigma(k).at n=31A027598
• A generalization of triangle A071951 (Legendre-Stirling).at n=16A089504
• Second column of triangle A089504 and second column of array A078741 divided by 18.at n=4A089507
• Triangle of scaled second column sequences of (k,k)-Stirling2 arrays.at n=23A091039
• Sixth column of (1,5)-Pascal triangle A096940.at n=29A096943
• Numbers k such that the squarefree kernel of sigma(k) is equal to the squarefree kernel of 2*k.at n=34A332208
• a(n) = n! * Sum_{k=1..n} 1/(k*floor(n/k)).at n=8A345682