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 A141409 #19 Jan 28 2022 04:08:10 %S A141409 2,3,5,7,11,13,17,19,29,31,41,43,47,59,61,67,71,79,83,89,97,101,103, %T A141409 107,109,127,131,139,149,151,157,163,167,179,181,191,199,223,227,233, %U A141409 239,251,263,269,277,281,307,337,349,353,373,401,409,419,421,431,439,443,449,457,461 %N A141409 Prime numbers that cannot be formed by the concatenation of previous terms. %C A141409 Previous terms can appear in any order but can be used at most once. - _Paolo P. Lava_, Mar 04 2010 %H A141409 David A. Corneth, <a href="/A141409/b141409.txt">Table of n, a(n) for n = 1..10000</a> %H A141409 David A. Corneth, <a href="/A141409/a141409.gp.txt">PARI program</a> %e A141409 137 is not in the sequence because 13 || 7 -> 137; %e A141409 797 is not in the sequence because 7 || 97 or 79 || 7 -> 797. %e A141409 257 is not in the sequence because 2 || 5 || 7 = 257 where || denotes concatenation. - _David A. Corneth_, Jan 23 2022 %o A141409 (PARI) See Corneth link \\ _David A. Corneth_, Jan 23 2022 %Y A141409 Cf. A141033. %K A141409 nonn,easy,base %O A141409 1,1 %A A141409 _Paolo P. Lava_ and _Giorgio Balzarotti_, Aug 04 2008, Aug 28 2008, Mar 04 2010 %E A141409 Offset changed to 1 and data corrected by _David A. Corneth_, Jan 23 2022