256751

Appears in sequences

• Numbers k such that sigma(phi(k))-phi(sigma(k)) is nonzero and is divisible by (k+1), that is A065395(k)/(k+1) = (phi(sigma(k))-sigma(phi(k)))/(k+1) is a nonzero integer.at n=18A092586
• Triangle read by rows: T(n,k) is the number of non-equivalent subsets of size k in S_n, 0 <= k <= n!.at n=45A381842