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 A128784 #16 Aug 31 2025 18:02:10
%S A128784 0,5,100,1125,10000,78125,562500,3828125,25000000,158203125,976562500,
%T A128784 5908203125,35156250000,206298828125,1196289062500,6866455078125,
%U A128784 39062500000000,220489501953125,1235961914062500,6885528564453125,38146972656250000,210285186767578125
%N A128784 a(n) = n^2*5^n.
%H A128784 Harvey P. Dale, <a href="/A128784/b128784.txt">Table of n, a(n) for n = 0..1000</a>
%H A128784 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (15,-75,125).
%F A128784 From _Harvey P. Dale_, Dec 30 2011: (Start)
%F A128784 a(0)=0, a(1)=5, a(2)=100, a(n) = 15*a(n-1)-75*a(n-2)+125*a(n-3).
%F A128784 G.f.: -5*(5*x^2+x)/(5*x-1)^3. (End)
%t A128784 Table[n^2 5^n,{n,0,20}] (* or *) LinearRecurrence[{15,-75,125},{0,5,100},20] (* _Harvey P. Dale_, Dec 30 2011 *)
%o A128784 (PARI) a(n)=n^2*5^n \\ _Charles R Greathouse IV_, May 16 2018
%Y A128784 Cf. A036289, A007758.
%K A128784 nonn,easy,changed
%O A128784 0,2
%A A128784 _Mohammad K. Azarian_, Apr 07 2007