102856

Appears in sequences

• Numbers k such that phi(k) = sigma(core(k)) where phi(k) is the Euler totient function, sigma(k) the sum of divisors of k and core(k) the squarefree part of k (the smallest integer such that k*core(k) is a square).at n=13A069552
• Numbers n such that sigma(n) = 5*phi(n).at n=14A136547
• G.f. A(x) satisfies: A(x) = x + 2*B(x)*C(x), where B(x) = x + 3*A(x)*C(x) and C(x) = x + 5*A(x)*B(x).at n=6A229808
• a(n) = number of subsets S of {1,2,...,n} having more than 2 elements such that (sum of least three elements of S) < max(S).at n=17A357285
• Number of permutations that end with a consecutive pattern 123, and avoid consecutive patterns 123 and 213 elsewhere.at n=12A371943
• Numbers k such that sigma(k) = psi(k) + phi(k).at n=21A389478