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 A339676 #33 Dec 16 2020 15:12:14
%S A339676 161051,1490841,1625151,1771561,14921841,15043941,16266151,16399251,
%T A339676 17876661,19487171,137009631,149231841,149352841,150574941,151807041,
%U A339676 162676151,164140251,165483351,178927661,180391761,196643271,214358881,1370219631,1371330631,1492331841
%N A339676 Nonpalindromic numbers that are products of repunits.
%C A339676 The first term is A308365(19).
%C A339676 G. J. Simmons conjectured there are no palindromes of form n^k for k >= 5 (and n > 1) (see link, page 98). According to this conjecture, these perfect powers are terms: {11^k, k>=4}, {111^k, k>=4}, {1111^k, k>=3}, {11111^k, k>=3}, ...
%H A339676 David A. Corneth, <a href="/A339676/b339676.txt">Table of n, a(n) for n = 1..10000</a>
%H A339676 Gustavus J. Simmons, <a href="https://oeis.org/A002778/a002778_2.pdf">Palindromic Powers</a>, J. Rec. Math., 3 (No. 2, 1970), 93-98 [Annotated scanned copy].
%e A339676 a(1) = 161051 = 11^5.
%e A339676 a(2) = 1490841 = 11^2 * 111^2.
%e A339676 a(3) = 1625151 = 11^4 * 111.
%e A339676 a(4) = 1771561 = 11^6.
%e A339676 a(5) = 14921841 = 11^2 * 111 * 1111.
%t A339676 vec[max_] := Module[{m = Floor @ Log10[9*max + 1], r, s = {1}, s1}, r = (10^Range[2, m] - 1)/9; Do[emax = Floor@Log[r[[k]], max]; s1 = r[[k]]^Range[0, emax]; s = Select[Union[Flatten[Outer[Times, s, s1]]], # <= max &], {k, 1, m - 1}]; s]; Select[vec[1.5*10^9], !PalindromeQ[#] &] (* _Amiram Eldar_, Dec 12 2020 *)
%Y A339676 Intersection of A308365 and A029742.
%Y A339676 Cf. A083278, A334131.
%K A339676 nonn,base
%O A339676 1,1
%A A339676 _Bernard Schott_, Dec 12 2020