419218787domain: NAppears in sequencesConsider the harmonic progression 1,1/2,1/3,1/4,1/5,..., group the terms such that the n-th group contains n members like this (1/1),(1/2,1/3),(1/4,1/5,1/6), (1/7,1/8,1/9,1/10),... a(n) = the numerator of the reduced rational sum of the terms of the n-th group.at n=7A081971