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 A076442 #12 Mar 14 2020 05:55:26
%S A076442 1,9,1331,3375,35937,59319,357911,753571,759375,5177717,5359375,
%T A076442 5735339,9393931,17373979,37595375,39135393,37159393753,99317171591,
%U A076442 175333911173,397551775977,1913551573375,9735913353977,11997979755957,17171515157399,335571975137771
%N A076442 Odd-digit perfect powers.
%C A076442 a(19) > 1.3*10^11. - _Robert G. Wilson v_, Dec 17 2002
%H A076442 Giovanni Resta, <a href="/A076442/b076442.txt">Table of n, a(n) for n = 1..566</a> (terms < 10^57)
%t A076442 NextOddNbr[n_] := Block[{d = If[ EvenQ[n], IntegerDigits[n + 1], IntegerDigits[n + 2]], l}, l = Length[d]; While[l != 1, If[ EvenQ[ d[[l]]], d[[l]]++ ]; If[d[[l]] > 9, d[[l - 1]]++; d[[l]] = 1]; l-- ]; If[ EvenQ[ d[[1]]], d[[1]]++ ]; If[ d[[1]] > 9, d[[1]] = 11]; FromDigits[d]] k = 1; Do[ If[ !PrimeQ[k] && Apply[GCD, Last[ Transpose[ FactorInteger[k]]]] > 1, Print[k]]; k = NextOddNbr[k], {n, 1, 10^8}]
%Y A076442 Cf. A001597, A014261, A075787.
%K A076442 nonn,base
%O A076442 1,2
%A A076442 _Robert G. Wilson v_ and _Zak Seidov_, Oct 11 2002
%E A076442 Extended by _Robert G. Wilson v_, Dec 17 2002
%E A076442 Terms a(19) and beyond from _Giovanni Resta_, Mar 13 2020