50539domain: NPropertiesPrimalityPrimeyesAppears in sequencesn is equal to the number of 2's in all numbers <= n written in base 6.at n=13A014891Concatenation of n, n+1, n+2 divided by 3.at n=15A074991Primes arising in A073946.at n=21A113943Primes generated by concatenation of three consecutive numbers divided by three.at n=2A226041Prime numbersat n=5183