229441

Appears in sequences

• Composite numbers k such that the sum of the divisors of k^2 is a prime.at n=37A065405
• a(n) is the least number x such that gcd(sigma(x), sigma(x+1)) = n.at n=42A084307
• Perfect squares which can be written neither as a^2+b^2, nor as a^2+2*b^2, nor as a^2+3*b^2, nor as a^2+7*b^2, with a > 0 and b > 0.at n=5A216408
• Numbers x such that x = concatenate(a, b) and phi(a) + phi(b) = sigma(x) - x.at n=18A254624
• Perfect powers k such that A052409(k) is equal to A052409(A366275(k)).at n=17A366278