a(n) = (10^(2n+1)-1)/3 + 4*10^n.A332137a(n) = (10^(2n+1)-1)/3 + 4*10^n.Terms a(0) =7a(1) =373a(2) =33733a(3) =3337333a(4) =333373333a(5) =33333733333External referencesoeis: A332137