4206121

Appears in sequences

• Numbers k that divide the alternating sum phi(1) - phi(2) + phi(3) - phi(4) + ... + ((-1)^(k+1))*phi(k).at n=24A067929
• G.f. A(x) satisfies A(x) = Sum_{k>=0} (k*x)^k * A(k*x).at n=7A385585