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 A175770 #15 Feb 02 2021 02:09:13
%S A175770 2,1,5,7,33,31,37,39,21,29,13,17,43,41,47,51,59,63,67,73,71,79,81,89,
%T A175770 97,303,301,307,309,331,327,313,317,319,349,353,357,361,367,371,379,
%U A175770 383,393,391,397,399,233,221,227,229,211,219,243,253,257,261,269,273,277
%N A175770 In the sequence of prime numbers, replace all the '3' digits with '1' and vice versa.
%H A175770 Vincenzo Librandi, <a href="/A175770/b175770.txt">Table of n, a(n) for n = 1..1000</a>
%t A175770 FromDigits[IntegerDigits[#]/.{3->p, 1->q}/.{p->1, q->3}]&/@Prime[Range[60]] (* _Vincenzo Librandi_, Jul 29 2013 *)
%o A175770 (PARI) a(n)=my(v=[0,3,2,1,4,5,6,7,8,9]);apply(k->v[k+1],digits(prime(n))) \\ _Charles R Greathouse IV_, Jul 16 2013
%o A175770 (Python)
%o A175770 from sympy import prime
%o A175770 def a(n):
%o A175770 return int(str(prime(n)).translate({ord('1'):ord('3'), ord('3'):ord('1')}))
%o A175770 print([a(n) for n in range(1, 60)]) # _Michael S. Branicky_, Feb 01 2021
%Y A175770 Cf. A000040 (the prime numbers), A171013-A171016, A171018-A171057.
%K A175770 nonn,base,easy
%O A175770 1,1
%A A175770 _Vincenzo Librandi_, Sep 01 2010
%E A175770 Corrected by _D. S. McNeil_ and _R. J. Mathar_, Sep 02 2010