217360domain: NAppears in sequencesNumber of 5 X n 0..1 arrays avoiding 0 0 1 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.at n=10A207256Numbers k such that R_(k+2) + 10^k is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=4A256925