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 A264406 #52 Jan 12 2016 00:18:21 %S A264406 1,11,101,111,1001,1111,10001,10101,10201,11011,11111,100001,101101, %T A264406 102201,110011,111111,1000001,1001001,1002001,1010101,1011101,1012101, %U A264406 1020201,1021201,1022201,1023201,1100011,1101011,1102011,1110111,1111111,10000001,10011001,10022001,10100101,10111101,10122101,10200201,10211201,10222201,10233201,11000011,11011011,11022011,11100111,11111111 %N A264406 Smallest palindrome of each distinct decimal type (A002113) in increasing order. %C A264406 Only positive palindromes are considered. %C A264406 The numbers N(n) of distinct types of n-digit palindromes, for n=1,2,..., are 1,1,2,2,5,5,15,15,... (A164904, n>=1). It is easy to see that N(2*n-1)=N(2*n), n>=1. %H A264406 Peter J. C. Moses, <a href="/A264406/b264406.txt">Table of n, a(n) for n = 1..6450</a> %e A264406 The type corresponding to the term 1021201 has the form XYZXZYX, where X,Y,Z are distinct decimal digits, X>0. %Y A264406 Cf. A002113, A164904. %K A264406 nonn,base %O A264406 1,2 %A A264406 _Vladimir Shevelev_, Dec 10 2015 %E A264406 Two missed terms were found by _Peter J. C. Moses_, Jan 07 2016