248882domain: NAppears in sequencesa(n) = 10n+12^n.at n=4A173393a(1) = 1, a(2) = 2, a(3) = 3; for n > 3, a(n) is the smallest positive number which has not appeared such that all the distinct prime factors of a(n-3) + a(n-2) + a(n-1) are factors of a(n).at n=39A361593