2640704

Appears in sequences

• Euler totient function (A000010) of 2^n - 1.at n=21A053287
• A062401(x)=phi[sigma(x)] function is iterated; initial value=2^n; a(n)=largest term of trajectory.at n=20A096999
• a(n) = phi(4^n-1), where phi is Euler's totient function (A000010).at n=10A295501