a(n) = 7*(10^(2*n+1) - 1)/9 - 10^n.A332176a(n) = 7*(10^(2*n+1) - 1)/9 - 10^n.Terms a(0) =6a(1) =767a(2) =77677a(3) =7776777a(4) =777767777a(5) =77777677777External referencesoeis: A332176