406898311domain: NPropertiesPrimalityPrimeyesAppears in sequencesExpansion of g.f. 1/((1-2*x)*(1-5*x)).at n=12A016127New factors appearing in the factorization of 5^k - 2^k as k increases.at n=14A109291Primes of form (5^n - 2^n)/3.at n=3A139781Prime numbersat n=21684351