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 A171022 #9 Mar 31 2017 20:29:14
%S A171022 2,4,5,7,11,14,17,19,24,29,41,47,31,34,37,54,59,61,67,71,74,79,84,89,
%T A171022 97,101,104,107,109,114,127,141,147,149,139,151,157,164,167,174,179,
%U A171022 181,191,194,197,199,211,224,227,229,244,249,231,251,257,264
%N A171022 In the sequence of prime numbers, replace all the '4' digits with '3' and vice versa.
%H A171022 Vincenzo Librandi, <a href="/A171022/b171022.txt">Table of n, a(n) for n = 1..1000</a>
%t A171022 FromDigits[IntegerDigits[#]/.{4->p, 3->q}/.{p->3, q->4}]&/@Prime[Range[100]] (* _Vincenzo Librandi_, Apr 07 2013 *)
%o A171022 (PARI) a(n)=my(v=[0,1,2,4,3,5,6,7,8,9]);subst(Pol(apply(k->v[k+1], digits(prime(n)))),'x,10) \\ _Charles R Greathouse IV_, Jul 16 2013
%K A171022 nonn,base,easy
%O A171022 1,1
%A A171022 _N. J. A. Sloane_ and _Vincenzo Librandi_, Sep 04 2010