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 A049390 #7 Dec 14 2017 19:39:00
%S A049390 1,-20,-50,-500,-6875,-110000,-1925000,-35750000,-692656250,
%T A049390 -13853125000,-283989062500,-5937953125000,-126181503906250,
%U A049390 -2717755468750000,-59208244140625000,-1302581371093750000
%N A049390 Expansion of (1-25*x)^(4/5).
%F A049390 G.f.: (1-25*x)^(4/5).
%F A049390 a(n) = 5^n/n! * product[ k=0..n-1 ] (5*k-4).
%F A049390 a(n) ~ -4/5*Gamma(1/5)^-1*n^(-9/5)*5^(2*n)*{1 + 18/25*n^-1 + ...}. - Joe Keane (jgk(AT)jgk.org), Nov 24 2001
%e A049390 (1-x)^(4/5) = 1 - 4/5*x - 2/25*x^2 - 4/125*x^3 - ...
%t A049390 CoefficientList[Series[(1-25x)^(4/5),{x,0,20}],x] (* _Harvey P. Dale_, Dec 14 2017 *)
%Y A049390 Cf. A034688.
%K A049390 sign,easy
%O A049390 0,2
%A A049390 Joe Keane (jgk(AT)jgk.org)
%E A049390 Definition adjusted by _Harvey P. Dale_, Dec 14 2017.