100542

Appears in sequences

• Numbers n such that 3*10^n + 8*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=23A102980
• a(n) = (2n-1)!! * Sum_{k=0..n-2}(-1)^k/(2k+1).at n=6A135457