862471domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(n) is the smallest prime such that it and the previous four primes are all of the form x^2 + n * y^2.at n=5A212605a(n) = Sum_{j=1..n} Sum_{k=1..n} sigma(j*k).at n=34A372675Prime numbersat n=68536