a(n) = 5*(10^(2*n+1)-1)/9 - 10^n.A332154a(n) = 5*(10^(2*n+1)-1)/9 - 10^n.Terms a(0) =4a(1) =545a(2) =55455a(3) =5554555a(4) =555545555a(5) =55555455555External referencesoeis: A332154