129504

Appears in sequences

• Numbers k such that phi(k) is equal to A008473(k).at n=18A039779
• Numbers n such that the arithmetic, geometric and harmonic means of phi(n) and sigma(n) are all integers.at n=34A065146
• Balanced refactorable numbers.at n=12A078543
• a(n) = Sum_{k=0..n} binomial(2*n,k)*binomial(n,k)*binomial(2*k,n).at n=5A103870
• Amicable triples: numbers such that sigma(x) = sigma(y) = sigma(z) = x+y+z, x<y<z. We order these triples according to the common value of sigma. Sequence gives y numbers.at n=24A125491
• Numbers k such that sigma(k) = 9*phi(k).at n=17A163667
• Number of subsets of {1..n} that can be linearly combined using nonnegative coefficients to obtain n.at n=17A365073