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 A034845 #15 May 20 2025 21:32:48
%S A034845 13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,113,199,
%T A034845 211,223,227,229,233,277,311,331,337,433,443,449,499,557,577,599,661,
%U A034845 677,733,773,811,877,881,883,887,911,977,991,997,1117,1777,1999,2111
%N A034845 Primes of the form iii...ijjj...j, i != j.
%H A034845 Alois P. Heinz, <a href="/A034845/b034845.txt">Table of n, a(n) for n = 1..10034</a> (first 1000 terms from Sean A. Irvine)
%t A034845 Select[Union[Flatten[Table[FromDigits[Join[PadRight[{},n,m],PadRight[{},k,q]]],{n,3},{m,9},{k,3},{q,{1,3,7,9}}]]],IntegerDigits[#][[1]]!=IntegerDigits[#][[-1]]&&PrimeQ[#]&] (* _Harvey P. Dale_, Apr 06 2022 *)
%Y A034845 Cf. A235154.
%K A034845 nonn,base
%O A034845 1,1
%A A034845 _Erich Friedman_