2802277domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes p of the form 4*n^2 + 1 such that 4*p^2+1 is also prime.at n=18A121834Primes of the form n^2+1 such that (n+2)^2+1 is also prime.at n=21A206328Prime numbersat n=203512