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 A072017 #15 Aug 27 2024 09:16:47 %S A072017 2899999989,2989999899,2999889999,3799999899,3898989999,3899799999, %T A072017 3899999988,3979989999,3988899999,3989999898,3989999979,3998999889, %U A072017 3999889998,3999898989,3999899799,3999979989,3999988899,4699998999 %N A072017 Numbers k such that gcd(k, reverse(k)) = 81 = 3^4, where reverse(x) = A004086(x). %C A072017 Numerous solutions can be constructed by inserting strings of suitable digits between digits of terms in A071016. %H A072017 Sean A. Irvine, <a href="/A072017/b072017.txt">Table of n, a(n) for n = 1..1000</a> %e A072017 k = 3*3*3*3*3*449*64157 and reverse(k) = 2*2*3*3*3*3*31*67*14827, GCD = 81. %Y A072017 Cf. A004086, A055483, A069554, A071686, A072005, A072016, A072018. %K A072017 nonn,base %O A072017 1,1 %A A072017 _Labos Elemer_, Jun 05 2002