1547536

Appears in sequences

• Starting from a(1)=7, each subsequent term is the minimal square obtained by inserting at least one digit into the previous term.at n=4A068616
• Least number x such that gcd(phi(x), sigma(x)) = n.at n=30A073815
• Smallest number m such that GCD(a+b,a-b) = n, where a = sigma(m) and b = phi(m).at n=30A077102
• Least x=a(n) such that product of common prime-divisors [without multiplicity] of sigma(x) and phi(x) equals n; or 0 if n is not a squarefree number or if no such x exists. Among indices n only squarefree numbers arise because multiplicity of prime factors is ignored.at n=30A082057