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 A047739 #17 May 19 2021 00:29:05
%S A047739 343,1331,10201,14641,31213,94249,1030301,1332331,1367631,1478741,
%T A047739 2060602,2513152,2551552,2570752,2939392,2977792,3090903,3498943,
%U A047739 3637363,3735373,3850583,5221225,5265625,5734375,6948496,11288211,11333311,12100121,12499421,13577531,14655641,22666622,27700772,29399392,31244213,33999933,38988983,58344385,71111117,100020001,100585001,101000101,104060401,104555401,106878601
%N A047739 Economical palindromes.
%e A047739 343 = 7^3; 3 digits in 343, 2 digits in 7^3, so 343 is economical.
%t A047739 d[n_]:=IntegerDigits[n]; palQ[n_]:=Reverse[(x=d[n])]==x; ecQ[n_]:=Length[Flatten[d[{First/@(x=FactorInteger[n]), DeleteCases[Last/@x,1]}]]] < Length[d[n]]; t={}; Do[If[palQ[n] && ecQ[n], AppendTo[t,n]], {n,3860000}]; t (* _Jayanta Basu_, May 16 2013 *)
%Y A047739 Cf. A002113, A046759.
%K A047739 nonn,base
%O A047739 1,1
%A A047739 _Carlos Rivera_
%E A047739 a(11)-a(45) from _Donovan Johnson_, Nov 24 2010