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%I #4 Sep 04 2022 15:51:40
%S 9,169,12769,1238769,123498769,12346098769,1234572098769,
%T 123456832098769,12345679432098769,1234567905432098769,
%U 123456790165432098769
%N a(n) = (n 1's followed by a 3)^2.
%C Is it true that the decimal expansion of a(n) contains no palindromic substrings of length greater than one?
%F 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 {3.9}
%e {13,169}
%e {113,12769}
%e {1113,1238769}
%e {11113,123498769}
%e {111113,12346098769}
%e {1111113,1234572098769}
%e {11111113,123456832098769}
%e {111111113,12345679432098769}
%e {1111111113,1234567905432098769}
%e {11111111113,123456790165432098769}
%t Table[FromDigits[PadLeft[{3},n,1]]^2,{n,20}] (* _Harvey P. Dale_, Sep 04 2022 *)
%Y Cf. A052061, A052062.
%K nonn,base
%O 0,1
%A Zak Seidov, Sep 09 2009
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