56679

Appears in sequences

• Numbers k such that sigma(phi(k)) = sigma(k) where sigma is the sum of divisors function A000203 and phi is the Euler totient function A000010.at n=17A033631
• Triangle of coefficients T(n,k) of x^n*y^k in g.f. A(x,y) satisfying y = Sum_{n=-oo..+oo} (-1)^n * x^n * (y*A(x,y) + x^(n-1))^(n+1).at n=57A359670
• Column 2 of triangle A359670; a(n) = A359670(n+2,2) for n >= 0.at n=8A359715