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 A171030 #9 Mar 31 2017 20:25:28
%S A171030 6,3,5,7,11,13,17,19,63,69,31,37,41,43,47,53,59,21,27,71,73,79,83,89,
%T A171030 97,101,103,107,109,113,167,131,137,139,149,151,157,123,127,173,179,
%U A171030 181,191,193,197,199,611,663,667,669,633,639,641,651,657,623
%N A171030 In the sequence of prime numbers, replace all the '6' digits with '2' and vice versa.
%H A171030 Vincenzo Librandi, <a href="/A171030/b171030.txt">Table of n, a(n) for n = 1..1000</a>
%t A171030 FromDigits[IntegerDigits[#]/.{6->p, 2->q}/.{p->2, q->6}]&/@Prime[Range[100]] (* _Vincenzo Librandi_, Apr 07 2013 *)
%o A171030 (PARI) a(n)=my(v=[0,1,6,3,4,5,2,7,8,9]);subst(Pol(apply(k->v[k+1], digits(prime(n)))),'x,10) \\ _Charles R Greathouse IV_, Jul 24 2013
%K A171030 nonn,base,easy
%O A171030 1,1
%A A171030 _N. J. A. Sloane_ and _Vincenzo Librandi_, Sep 04 2010