This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A151997 #4 Sep 04 2022 15:51:40
%S A151997 9,169,12769,1238769,123498769,12346098769,1234572098769,
%T A151997 123456832098769,12345679432098769,1234567905432098769,
%U A151997 123456790165432098769
%N A151997 a(n) = (n 1's followed by a 3)^2.
%C A151997 Is it true that the decimal expansion of a(n) contains no palindromic substrings of length greater than one?
%F A151997 a(n) = (100^(n+1)+340*10^n+289)/81. a(n)= 111*a(n-1) -1110*a(n-2) +1000*a(n-3). G.f.: (9-830*x+4000*x^2)/((1-x) * (100*x-1) * (10*x-1)). [From _R. J. Mathar_, Sep 15 2009]
%e A151997 {3.9}
%e A151997 {13,169}
%e A151997 {113,12769}
%e A151997 {1113,1238769}
%e A151997 {11113,123498769}
%e A151997 {111113,12346098769}
%e A151997 {1111113,1234572098769}
%e A151997 {11111113,123456832098769}
%e A151997 {111111113,12345679432098769}
%e A151997 {1111111113,1234567905432098769}
%e A151997 {11111111113,123456790165432098769}
%t A151997 Table[FromDigits[PadLeft[{3},n,1]]^2,{n,20}] (* _Harvey P. Dale_, Sep 04 2022 *)
%Y A151997 Cf. A052061, A052062.
%K A151997 nonn,base
%O A151997 0,1
%A A151997 Zak Seidov, Sep 09 2009