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 A186208 #16 Sep 15 2017 23:16:10
%S A186208 3,67,367,7879,36787,367879,8794411,21595523,867445811,2159552377,
%T A186208 23215955237,794411714423,9441171442321,57147274345919,
%U A186208 767834507836801,4581113103176783,67834507836801697,595523770161460867,3176783450783680169
%N A186208 The first n-digit prime in the decimal expansion of 1/e.
%C A186208 1/e = 0.36787944117144232159....
%H A186208 Matthew House, <a href="/A186208/b186208.txt">Table of n, a(n) for n = 1..996</a>
%p A186208 Digits := 10000: p0 := evalf(1/exp(1))*10:for d from 1 to 20 do: id:=0:for
%p A186208 i from 0 to 50000 while(id=0) do :q0:=trunc(p0*10^(i+d-1)): x:= irem(q0,10^d):
%p A186208 if type(x,prime)=true and length(x)=d then printf(`%d, `,x):id:=1: else fi:od:od:
%t A186208 With[{x=RealDigits[1/E,10,1000][[1]]},Table[FromDigits[ First[ Select[ Partition[x,n,1],PrimeQ[FromDigits[#]]&]]],{n,20}]] (* _Harvey P. Dale_, Feb 17 2011 *)
%Y A186208 Cf. A001113, A095935.
%K A186208 nonn,base
%O A186208 1,1
%A A186208 _Michel Lagneau_, Feb 15 2011