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 A054616 #16 Apr 17 2021 01:26:09
%S A054616 0,9,90,747,6660,59085,532350,4783023,43053480,387422001,3486843810,
%T A054616 31381059699,282430082700,2541865828437,22876797238470,
%U A054616 205891132215735,1853020231912080,16677181699666713,150094635685484490,1350851717672992251
%N A054616 a(n) = Sum_{d|n} phi(d)*9^(n/d).
%H A054616 Seiichi Manyama, <a href="/A054616/b054616.txt">Table of n, a(n) for n = 0..1000</a>
%F A054616 a(n) = Sum_{k=1..n} 9^gcd(n,k). - _Ilya Gutkovskiy_, Apr 16 2021
%o A054616 (PARI) a(n) = if(n==0, 0, sumdiv(n, d, eulerphi(d)*9^(n/d))); \\ _Altug Alkan_, Mar 16 2018
%Y A054616 Column k=9 of A185651.
%Y A054616 Cf. A054628.
%K A054616 nonn
%O A054616 0,2
%A A054616 _N. J. A. Sloane_, Apr 16 2000