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 A342725 #11 Mar 21 2021 01:05:06
%S A342725 0,1,13,17,189,205,257,273,3005,3069,3277,3341,4033,4097,4305,4369,
%T A342725 48061,48317,49149,49405,52173,52429,53261,53517,64449,64705,65537,
%U A342725 65793,68561,68817,69649,69905,768957,769981,773309,774333,785405,786429,789757,790781,834509
%N A342725 Numbers that are palindromic in base i-1.
%H A342725 Amiram Eldar, <a href="/A342725/b342725.txt">Table of n, a(n) for n = 1..512</a>
%H A342725 Walter Penney, <a href="http://dx.doi.org/10.1145/321264.321274">A "binary" system for complex numbers</a>, Journal of the ACM, Vol. 12, No. 2 (1965), pp. 247-248.
%F A342725 13 is a term since its base-(i-1) presentation is 100010001 which is palindromic.
%t A342725 v = {{0, 0, 0, 0}, {0, 0, 0, 1}, {1, 1, 0, 0}, {1, 1, 0, 1}}; q[n_] := PalindromeQ @ FromDigits[Flatten @ v[[1 + Reverse @ Most[Mod[NestWhileList[(# - Mod[#, 4])/-4 &, n, # != 0 &], 4]]]]]; Select[Range[0, 10^4], q]
%Y A342725 Cf. A066321, A066323, A271472, A342726, A342727, A342728, A342729.
%Y A342725 Similar sequences: A002113 (decimal), A006995 (binary), A014190 (base 3), A014192 (base 4), A029952 (base 5), A029953 (base 6), A029954 (base 7), A029803 (base 8), A029955 (base 9), A046807 (factorial base), A094202 (Zeckendorf), A331191 (dual Zeckendorf), A331891 (negabinary), A333423 (primorial base).
%K A342725 nonn,base
%O A342725 1,3
%A A342725 _Amiram Eldar_, Mar 19 2021