50437domain: NAppears in sequencesIndices of primes at which the prime race 4k-1 vs. 4k+1 is tied.at n=25A038691Numbers k such that sigma(k - 2) = sigma(k + 2).at n=37A223091Number of arrays of median of three adjacent elements of some length-5 0..n array, with no adjacent equal elements in the latter.at n=35A229013