46455domain: NAppears in sequencesNumbers 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=17A102941Integers of the form 8k+7 that can be written as a sum of four distinct squares of the form m, m+2, m+4, m+5, where m == 1 (mod 4).at n=26A243579