38615domain: NAppears in sequencesa(n) = a(n-1) + a(n-2) + 1, with a(0) = 1 and a(1) = 7.at n=19A022321Decimal part of cube root of a(n) starts with 8: first term of runs.at n=32A034134Numbers whose base-14 representation has exactly 5 runs.at n=2A043666a(1)=1. a(n) = Sum_{1<=k<n, gcd(k,n(n+1))=1} a(k).at n=44A125596