115807domain: NPropertiesPrimalityPrimeyesAppears in sequencesNumbers n such that 257*2^n+1 is prime.at n=3A032505Duplicate of A032505.at n=3A053345Number of n X n binary arrays symmetric about both diagonal and antidiagonal with all ones connected only in a 1001-1001-1111 pattern in any orientation.at n=21A147409Prime numbersat n=10943