| Let {Bn}n≥0 and {Nn}n≥0 be the Balancing and the Narayana’s cow sequences given by the initial conditions B0=0,B1=1,N0=0,N1=N2=N3=1 and the recurrence formulas Bn+1=6Bn-Bn-1(n≥1)Nn=Nn-1+Nn-3(n≥3),respectively.In this paper,we proved that Balancing numbers which are concatenations of three repdigits,and Narayana numbers and the products of two Narayana numbers which are close to Balancing numbers by using the linear forms in logarithms of algebraic numbers and the Baker-Davenport reduction methods.Let Z+ be a positive integer set,and the following results are obtained:1.Let a1,s1,s2,s3∈Z+,a1,a2,a3={0,1,…,9}.a1≠a2 and a2≠a3,then Diophantine equation(?) has positive integer solutions(n,Bn)∈{(4,204),(5,1189)}.2.Let n,k∈ Z+,then Diophantine inequality |Nn-Bk|<Bk1/2 has positive integer solutions(n,k)∈{(1,1),(2,1),(3,1),(6,2),(7,2)}.3.Let n,m,k ∈Z+ and 4 ≤m≤n,then Diophantine inequality|NnNm-Bk|<Bk1/2 has positive integer solutions(n,m,k)∈ {(4,4,2),(5,4,2),(6,4,2),(7,7,3),(8,6,3),(9,5,3),(10,4,3),(15,8,5),(18,5,5),(19,4,5)}. |