2335722480domain: NAppears in sequencesGroup the prime numbers so that the sum of the terms of the n-th group is a multiple of that of the (n-1)-st group: (2), (3,5), (7,11,13,17), (19,23,29,31,37...,79,83), ...; a(n) = sum of n-th group.at n=5A079802