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 A332184 #8 Feb 11 2020 08:28:31
%S A332184 4,848,88488,8884888,888848888,88888488888,8888884888888,
%T A332184 888888848888888,88888888488888888,8888888884888888888,
%U A332184 888888888848888888888,88888888888488888888888,8888888888884888888888888,888888888888848888888888888,88888888888888488888888888888,8888888888888884888888888888888
%N A332184 a(n) = 8*(10^(2n+1)-1)/9 - 4*10^n.
%H A332184 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (111,-1110,1000).
%F A332184 a(n) = 8*A138148(n) + 4*10^n = A002282(2n+1)- 4*10^n = 4*A332121(n).
%F A332184 G.f.: (4 + 404*x - 1200*x^2)/((1 - x)(1 - 10*x)(1 - 100*x)).
%F A332184 a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3) for n > 2.
%p A332184 A332184 := n -> 8*(10^(2*n+1)-1)/9-4*10^n;
%t A332184 Array[8 (10^(2 # + 1)-1)/9- 4*10^# &, 15, 0]
%o A332184 (PARI) apply( {A332184(n)=10^(n*2+1)\9*8-4*10^n}, [0..15])
%o A332184 (Python) def A332184(n): return 10**(n*2+1)//9*8-4*10**n
%Y A332184 Cf. A002275 (repunits R_n = (10^n-1)/9), A002282 (8*R_n), A011557 (10^n).
%Y A332184 Cf. A138148 (cyclops numbers with binary digits only).
%Y A332184 Cf. A332180 .. A332189 (variants with different middle digit 0, ..., 9).
%K A332184 nonn,base,easy
%O A332184 0,1
%A A332184 _M. F. Hasler_, Feb 08 2020