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 A171032 #9 Mar 31 2017 11:13:08
%S A171032 2,3,5,7,11,13,17,19,23,29,31,37,61,63,67,53,59,41,47,71,73,79,83,89,
%T A171032 97,101,103,107,109,113,127,131,137,139,169,151,157,143,147,173,179,
%U A171032 181,191,193,197,199,211,223,227,229,233,239,261,251,257,243
%N A171032 In the sequence of prime numbers, replace all the '6' digits with '4' and vice versa.
%H A171032 Vincenzo Librandi, <a href="/A171032/b171032.txt">Table of n, a(n) for n = 1..1000</a>
%t A171032 FromDigits[IntegerDigits[#]/.{6->p, 4->q}/.{p->4, q->6}]&/@Prime[Range[100]] (* _Vincenzo Librandi_, Apr 07 2013 *)
%o A171032 (PARI) a(n)=my(v=[0,1,2,3,6,5,4,7,8,9]);subst(Pol(apply(k->v[k+1], digits(prime(n)))),'x,10) \\ _Charles R Greathouse IV_, Jul 25 2013
%K A171032 nonn,base,easy
%O A171032 1,1
%A A171032 _N. J. A. Sloane_ and _Vincenzo Librandi_, Sep 04 2010