115810

Appears in sequences

• Numbers k such that 8*R_k + 7*10^k - 1 is prime, where R_k = 11...11 is the repunit (A002275) of length k.at n=8A259137
• a(n) = A289670(n)/2^f(n), where f(n) = 2*floor((n-1)/3) + ((n+2) mod 3).at n=55A289676
• a(n) = A289676(3*n+2).at n=18A290437