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 A320725 #36 Dec 14 2018 20:15:45 %S A320725 2,3,5,7,11,19,41,61,89,409,449,499,881,6469 %N A320725 Prime numbers such that all other numbers obtained from all permutations of all subsets of the digits are nonprime. %C A320725 Sequence is finite since it is a subsequence of a finite sequence (A071062). %C A320725 This is complete: there are only 14 terms in the sequence. %e A320725 449 is in this sequence because it's prime and none of the numbers 4, 9, 44, 49, 94, 494 and 944 is prime. %t A320725 Select[Prime@ Range[10^3], NoneTrue[DeleteCases[FromDigits /@ Rest@ Union@ Apply[Join, Permutations /@ Subsets@ IntegerDigits@ #], #], PrimeQ] &] (* _Michael De Vlieger_, Oct 22 2018 *) %Y A320725 Subsequence of A071062. %Y A320725 Cf. A320726 (the same for composite numbers). %K A320725 nonn,base,fini,full %O A320725 1,1 %A A320725 _Daniel Lignon_, Oct 19 2018