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 A171031 #9 Mar 31 2017 13:00:30
%S A171031 2,6,5,7,11,16,17,19,26,29,61,67,41,46,47,56,59,31,37,71,76,79,86,89,
%T A171031 97,101,106,107,109,116,127,161,167,169,149,151,157,136,137,176,179,
%U A171031 181,191,196,197,199,211,226,227,229,266,269,241,251,257,236
%N A171031 In the sequence of prime numbers, replace all the '6' digits with '3' and vice versa.
%H A171031 Vincenzo Librandi, <a href="/A171031/b171031.txt">Table of n, a(n) for n = 1..1000</a>
%t A171031 FromDigits[IntegerDigits[#]/.{6->p, 3->q}/.{p->3, q->6}]&/@Prime[Range[100]] (* _Vincenzo Librandi_, Apr 07 2013 *)
%o A171031 (PARI) a(n)=my(v=[0,1,2,6,4,5,3,7,8,9]);subst(Pol(apply(k->v[k+1], digits(prime(n)))),'x,10) \\ _Charles R Greathouse IV_, Jul 25 2013
%K A171031 nonn,base,easy
%O A171031 1,1
%A A171031 _N. J. A. Sloane_ and _Vincenzo Librandi_, Sep 04 2010