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 A171037 #11 Mar 31 2017 11:09:42
%S A171037 2,7,5,3,11,17,13,19,27,29,71,73,41,47,43,57,59,61,63,31,37,39,87,89,
%T A171037 93,101,107,103,109,117,123,171,173,179,149,151,153,167,163,137,139,
%U A171037 181,191,197,193,199,211,227,223,229,277,279,241,251,253,267
%N A171037 In the sequence of prime numbers, replace all the '7' digits with '3' and vice versa.
%H A171037 Vincenzo Librandi, <a href="/A171037/b171037.txt">Table of n, a(n) for n = 1..1000</a>
%t A171037 pq[n_]:=Module[{idn=IntegerDigits[n]},FromDigits[idn/.{7->p,3->q}/.{p->3,q->7}]]; pq/@Prime[Range[60]] (* _Harvey P. Dale_, Dec 11 2012 *)
%o A171037 (PARI) a(n)=my(v=[0,1,2,7,4,5,6,3,8,9]);subst(Pol(apply(k->v[k+1], digits(prime(n)))),'x,10) \\ _Charles R Greathouse IV_, Jul 25 2013
%K A171037 nonn,base,easy
%O A171037 1,1
%A A171037 _N. J. A. Sloane_ and _Vincenzo Librandi_, Sep 04 2010