2042039

Properties

Appears in sequences

• Primes of the form p*q + p + q, where (p, q=p+2) are twin primes.at n=17A065017
• a(n) = A126098(n) - 1.at n=34A117010
• Safe primes that are also highly cototient numbers.at n=19A209193
• a(n) = 8*(Product{i=1..n} p(i + 1)) - 1, where p(i) = i-th prime.at n=6A228698
• Primes of the form 8*Product{i=1..n} p(i) - 1, where p(i) = i-th odd prime.at n=4A228699
• a(n) is the smallest q such that the number of nonnegative k <= q, possessing the property that k + k*q - q is a square, is equal to 2^n.at n=8A332802
• Numbers k where records occur for phi(k)/phi(k+1), where phi is the Euler totient function (A000010).at n=37A335070
• Prime numbersat n=151844