189693

Appears in sequences

• Numbers k such that 10^k + 6*R_k + 3 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=21A102941
• Number of (n+3) X 5 0..1 matrices with each 4 X 4 subblock idempotent.at n=23A224562