102087domain: NAppears in sequencesGaps of 8 in sequence A038593 (lower terms).at n=34A038655a(1)=1; a(n) = Sum_{1<=k<n, gcd(k,n(n+1)/2)=1} a(k).at n=28A125597a(n) = T(n, 4) with T(n, k) = Sum_{d|k} phi(d)*binomial(n - 1 + k/d, k/d).at n=38A327032