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 A065723 #19 Dec 08 2024 20:41:34
%S A065723 2,3,13,23,41,71,83,101,163,191,211,281,283,311,331,463,503,571,613,
%T A065723 653,701,743,823,863,881,983,1091,1213,1231,1283,1301,1373,1381,1423,
%U A065723 1471,1493,1531,1543,1621,1741,1783,1861,1873,1931,2063,2203,2213,2221
%N A065723 Primes that when written in base 5, then reinterpreted in base 10, again give primes.
%C A065723 In general rebase notation (Marc LeBrun): p5 = (5) [p] (10).
%H A065723 Harry J. Smith, <a href="/A065723/b065723.txt">Table of n, a(n) for n = 1..1000</a>
%e A065723 E.g., 2213_10 = 32323_5 is prime, and so is 32323_10.
%t A065723 Select[ Range[2250], PrimeQ[ # ] && PrimeQ[ FromDigits[ IntegerDigits[ #, 5]]] & ]
%t A065723 Select[Prime[Range[400]],PrimeQ[FromDigits[IntegerDigits[#,5]]]&] (* _Harvey P. Dale_, Mar 28 2015 *)
%o A065723 (PARI) isok(p)={ isprime(p) && isprime(fromdigits(digits(p,5))) } \\ _Harry J. Smith_, Oct 27 2009
%Y A065723 Cf. A065720 up to A065727, A065361.
%K A065723 nonn,base
%O A065723 1,1
%A A065723 _Patrick De Geest_, Nov 15 2001