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 A226108 #24 Jul 23 2025 05:26:25
%S A226108 11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,113,
%T A226108 131,137,173,179,197,311,317,431,617,719,1117,1171,4111,11113,11117,
%U A226108 11119,11131,11171,11173,11197,11311,11317,11719,11731,13171,13711,41113
%N A226108 Primes remaining prime if all but two digits are deleted.
%C A226108 Subsequence of A069488.
%D A226108 C. Caldwell, Truncatable primes, J. Recreational Math., 19:1 (1987) 30-33.
%H A226108 Tim Cieplowski, <a href="/A226108/b226108.txt">Table of n, a(n) for n = 1..2720</a>
%H A226108 P. Ballew, <a href="http://pballew.blogspot.com/2013/05/knockout-primes-and-new-notation.html">Knockout Primes and a new notation</a>, May 17, 2013
%H A226108 C. Caldwell, <a href="https://t5k.org/glossary/xpage/DeletablePrime.html">The Prime Glossary: Deletable Prime</a>
%e A226108 For a(3)=137, all pairs of two digits (in their original order) 13, 17, and 37 are prime.
%t A226108 testQ[n_] := n > 9 && Catch[Block[{d = IntegerDigits@n}, Do[If[! PrimeQ[ d[[j]] + 10*d[[i]]], Throw@False], {j, 2, Length@d}, {i, j-1}]; True]]; Select[Prime@ Range[10^5], testQ] (* _Giovanni Resta_, May 28 2013 *)
%Y A226108 Cf. A019546, A051362, A069488.
%K A226108 nonn,base
%O A226108 1,1
%A A226108 _Tim Cieplowski_, May 26 2013