506251domain: NPropertiesPrimalityPrimeyesAppears in sequencesG.f. satisfies: A(x) = x^2 + x^3 + A(A(x)).at n=17A213905Least prime divisor of Fr(n) which does not divide any Fr(k) with k < n, or 1 if such a primitive prime divisor of Fr(n) does not exist, where Fr(n) denotes the n-th Franel number given by A000172.at n=18A242169Prime numbersat n=42007