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 A262777 #19 Apr 04 2016 23:28:12
%S A262777 8,97,995,9993,99989,999987,9999983,99999981,999999977,9999999971,
%T A262777 99999999969,999999999963,9999999999959,99999999999957,
%U A262777 999999999999953,9999999999999947,99999999999999941,999999999999999939,9999999999999999933
%N A262777 a(n) = 10^n - prime(n).
%e A262777 a(4) = 10^4-7=9993.
%t A262777 Table[10^n - Prime@ n, {n, 19}] (* _Michael De Vlieger_, Mar 24 2016 *)
%o A262777 (PARI) a(n) = 10^n - prime(n); \\ _Altug Alkan_, Mar 24 2016
%Y A262777 Cf. A000040, A011557, A193825.
%K A262777 nonn
%O A262777 1,1
%A A262777 _Emre APARI_, Mar 24 2016
%E A262777 More terms from _Altug Alkan_, Mar 24 2016