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 A135420 #9 Oct 13 2016 22:08:08
%S A135420 1,20,10000,125000000,39062500000000,305175781250000000000,
%T A135420 59604644775390625000000000000,
%U A135420 291038304567337036132812500000000000000,35527136788005009293556213378906250000000000000000
%N A135420 a(n) = 4^n * 5^(n^2).
%C A135420 Hankel transform of A132864.
%C A135420 For n>0, a(n) is even with a last digit of 0 and is 1 when n=0. - _Wesley Ivan Hurt_, Dec 04 2013
%H A135420 G. C. Greubel, <a href="/A135420/b135420.txt">Table of n, a(n) for n = 0..25</a>
%F A135420 a(n) = 4^n*5^(n^2) = A000302(n) * A060758(n).
%p A135420 A135420:=n->4^n*5^(n^2); seq(A135420(n), n=0..10); # _Wesley Ivan Hurt_, Dec 04 2013
%t A135420 Table[4^n*5^(n^2), {n,0,10}] (* _Wesley Ivan Hurt_, Dec 04 2013 *)
%K A135420 nonn
%O A135420 0,2
%A A135420 _Philippe Deléham_, Dec 11 2007