371519

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=21A092586
• Number of (w,x,y,z) with all terms in {1,...,n} and |x-y|>=|y-z|.at n=29A212682