41309

Appears in sequences

• Smallest solution m to (n+1)*phi(m) = n*sigma(m), or -1 if no solution exists.at n=39A065824
• a(n) = A065824(A047845(n+1)).at n=18A065884
• Least x = a(n) such that sum of common prime divisors (without multiplicity) of sigma(x) and phi(x) equals n, or 0 if such number (apparently) does not exist.at n=26A082056
• Numbers m such that m and m+2 are both brilliant numbers, where brilliant numbers are semiprimes whose prime factors have an equal number of decimal digits, or whose prime factors are equal.at n=22A083284
• Composite numbers n such that every divisor of n greater than one contains the digit 0.at n=9A243819
• Numerator of Sum_{i = 1..n} (if(isprime(i), 0, 1/i)).at n=21A282501
• Numerator of Sum_{i = 1..n} (if(isprime(i), 0, 1/i)).at n=22A282501
• Numerator of the sum of the reciprocals of the first n nonprimes.at n=13A282511
• Number of nX6 0..1 arrays with every element equal to 0, 1, 2 or 4 king-move adjacent elements, with upper left element zero.at n=18A297887