40743

Appears in sequences

• a(1) = 1; a(n) = 3 + n * Sum_{k=1..n-1} a(k).at n=6A082428
• Numbers n such that 8*10^n + 4*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=18A103079