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 A086042 #14 Jun 08 2025 16:15:42
%S A086042 31,71,73,97,101,103,107,109,131,173,193,197,271,293,307,311,317,373,
%T A086042 397,419,439,491,509,547,571,593,607,617,647,659,673,701,709,719,727,
%U A086042 733,739,743,751,757,761,809,839,907,919,937,941,947,953,971,983,991
%N A086042 Nontrivial numbers which are prime and yield another prime when their digits are sorted in ascending order.
%C A086042 Primes with digits already in ascending order (like 13 and 2357) are trivial cases and are therefore excluded.
%C A086042 See A211654 for the sequence including the trivial cases. - _M. F. Hasler_, Jul 30 2019
%H A086042 Harvey P. Dale, <a href="/A086042/b086042.txt">Table of n, a(n) for n = 1..1000</a>
%e A086042 a(1)=31 because an ascending sort of 31's digits yields 13 which is also prime. a(53)=1009 because an ascending sort of 1009's digits yields 19 which is also prime.
%t A086042 paoQ[n_]:=Module[{idn=IntegerDigits[n],sidn},sidn=Sort[idn];sidn!=idn && PrimeQ[FromDigits[sidn]]] (* _Harvey P. Dale_, Nov 14 2011 *)
%o A086042 (PARI) select( is_A086042(p,q=fromdigits(vecsort(digits(p))))={p>q&&isprime(q)&&isprime(p)}, [1..999]) \\ _M. F. Hasler_, Jul 30 2019
%o A086042 (Magma) [p:p in PrimesUpTo(1000)| IsPrime(Seqint(Reverse(Sort(Intseq(p,10))))) and p ne Seqint(Reverse(Sort(Intseq(p,10)))) ]; // _Marius A. Burtea_, Jul 30 2019
%Y A086042 Cf. A086402, A086051, A211654.
%K A086042 base,nonn
%O A086042 1,1
%A A086042 _Chuck Seggelin_, Jul 07 2003