203937090

Appears in sequences

• Numbers n such that 2n-1, 4n-1, 6n-1, 8n-1, 10n-1, 12n-1, 14n-1 and 16n-1 are primes.at n=4A124491
• a(n) = least k such that 2*i*k - 1 is prime for 1 <= i <= n.at n=8A124492