a(n) = (10^(2*n+1) - 1)/9 + 2*10^n.A332113a(n) = (10^(2*n+1) - 1)/9 + 2*10^n.Terms a(0) =3a(1) =131a(2) =11311a(3) =1113111a(4) =111131111a(5) =11111311111External referencesoeis: A332113