306181

Appears in sequences

• Hyperperfect numbers: k = m*(sigma(k) - k - 1) + 1 for some m > 1.at n=24A007592
• Hyperperfect numbers: x such that x = 1 + k*(sigma(x)-x-1) for some k > 0.at n=28A034897
• Nonsemiprime hyperperfect numbers.at n=9A133447
• Numbers x such that x = concatenate(a, b) and phi(a) + phi(b) = sigma(x) - x.at n=21A254624