322009domain: NPropertiesPrimalityPrimeyesAppears in sequencesPrimes containing the digits (2,0,0,9) in that order.at n=19A197114Number of (n+1)X(n+1) -9..9 symmetric matrices with every 2X2 subblock having sum zero and one, two or three distinct values.at n=9A211553Prime numbersat n=27769