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 A180543 #11 Oct 30 2023 11:14:46 %S A180543 3,7,13,17,31,37,43,47,71,73,103,107,137,139,163,167,173,179,193,197, %T A180543 223,227,233,277,337,347,353,379,383,439,463,467,479,613,617,643,647, %U A180543 739,743,757,773,787,823,827,853,857,883,887,1093,1097,1213,1217,1321 %N A180543 Primes that become a different prime under the mapping 3 <=> 7. %H A180543 Robert Price, <a href="/A180543/b180543.txt">Table of n, a(n) for n = 1..3168</a> %H A180543 <a href="/index/Pri#primes">Index to Primes</a>, Primes that become a different prime under some mapping. %t A180543 fQ[n_] := Block[{id = IntegerDigits@n}, (MemberQ[id, 3] || MemberQ[id, 7]) && PrimeQ[ FromDigits[ id /. {3 -> 7, 7 -> 3}] ]]; Select[ Prime@ Range@ 250, fQ] %Y A180543 Cf. A171037, A175791, A180517 thru A180559, A175789, A180560, A180561. %K A180543 base,nonn %O A180543 1,1 %A A180543 _Zak Seidov_ and _Robert G. Wilson v_, Sep 09 2010