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 A377192 #22 Nov 11 2024 02:21:19
%S A377192 0,10,1010,100110,10001110,1000011110,100000111110,10000001111110,
%T A377192 1000000011111110,100000000111111110,10000000001111111110,
%U A377192 1000000000011111111110,100000000000111111111110,10000000000001111111111110,1000000000000011111111111110,100000000000000111111111111110
%N A377192 Smallest number with the property that you have to change at least n digits to get a palindrome.
%C A377192 Positions of records in A377191.
%H A377192 Paolo Xausa, <a href="/A377192/b377192.txt">Table of n, a(n) for n = 0..450</a>
%H A377192 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (111,-1110,1000).
%F A377192 a(n) = 10^(2*n-1) + (10^n-1)/9 - 1 for n > 0.
%F A377192 From _Stefano Spezia_, Oct 20 2024: (Start)
%F A377192 G.f.: 10*x*(1 - 10*x - 90*x^2)/((1 - x)*(1 - 10*x)*(1 - 100*x)).
%F A377192 E.g.f.: (81 - 100*exp(x) + 10*exp(10*x) + 9*exp(100*x))/90. (End)
%F A377192 a(n) = A007088(A143960(n)) for n > 0. - _Rémy Sigrist_, Nov 05 2024
%e A377192 a(2) = 1010 because 1010 is the smallest number with the property that you have to change at least 2 digits to get a palindrome.
%t A377192 A377192[n_] := Ceiling[10^(2*n-1) + (10^n-1)/9 - 1]; Array[A377192, 20, 0] (* or *)
%t A377192 LinearRecurrence[{111, -1110, 1000}, {0, 10, 1010, 100110}, 20] (* _Paolo Xausa_, Nov 06 2024 *)
%Y A377192 Cf. A002113, A007088, A143960, A377191.
%K A377192 nonn,base,easy
%O A377192 0,2
%A A377192 _Franz Vrabec_, Oct 19 2024