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 A013894 #27 Jul 13 2025 17:08:43 %S A013894 20,64000000,204800000000000,655360000000000000000, %T A013894 2097152000000000000000000000,6710886400000000000000000000000000, %U A013894 21474836480000000000000000000000000000000,68719476736000000000000000000000000000000000000,219902325555200000000000000000000000000000000000000000 %N A013894 a(n) = 20^(5*n + 1). %H A013894 Vincenzo Librandi, <a href="/A013894/b013894.txt">Table of n, a(n) for n = 0..50</a> %H A013894 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>. %H A013894 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (3200000). %F A013894 a(n) = 3200000*a(n-1), a(0)=20. - _Vincenzo Librandi_, May 27 2011 %F A013894 From _Elmo R. Oliveira_, Jul 11 2025: (Start) %F A013894 G.f.: 20/(1-3200000*x). %F A013894 E.g.f.: 20*exp(3200000*x). %F A013894 a(n) = A013822(n)*A013854(n) = A009964(A016861(n)). (End) %t A013894 NestList[3200000*# &, 20, 10] (* _Paolo Xausa_, Jul 13 2025 *) %o A013894 (Magma) [20^(5*n+1): n in [0..10]]; // _Vincenzo Librandi_, May 27 2011 %Y A013894 Subsequence of A009964. %Y A013894 Cf. A013822, A013854, A016861. %K A013894 nonn,easy %O A013894 0,1 %A A013894 _N. J. A. Sloane_