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 A180534 #11 Oct 30 2023 11:13:37
%S A180534 23,43,223,229,233,239,241,257,263,421,433,439,443,449,457,463,521,
%T A180534 541,1249,1259,1283,1289,1429,1459,1483,1489,1523,1543,1721,1741,2003,
%U A180534 2029,2099,2111,2153,2221,2243,2251,2281,2293,2339,2347,2357,2411,2417,2423
%N A180534 Primes that become a different prime under the mapping 2 <=> 4.
%H A180534 Robert Price, <a href="/A180534/b180534.txt">Table of n, a(n) for n = 1..2470</a>
%H A180534 <a href="/index/Pri#primes">Index to Primes</a>, Primes that become a different prime under some mapping.
%t A180534 fQ[n_] := Block[{id = IntegerDigits@n}, (MemberQ[id, 2] || MemberQ[id, 4]) && PrimeQ[ FromDigits[ id /. {2 -> 4, 4 -> 2}] ]]; Select[ Prime@ Range@ 400, fQ]
%Y A180534 Cf. A171021, A175791, A180517 thru A180559, A175789, A180560, A180561.
%K A180534 base,nonn
%O A180534 1,1
%A A180534 _Zak Seidov_ and _Robert G. Wilson v_, Sep 09 2010