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 A320585 #30 Apr 02 2020 19:31:03 %S A320585 2,3,5,7,23,29,31,37,53,59,71,73,79,211,223,227,229,233,239,241,251, %T A320585 257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353, %U A320585 359,367,373,379,383,389,397,503,509,521,523,541,547,557,563,569,571 %N A320585 Primes whose first digit is prime. %H A320585 Robert Israel, <a href="/A320585/b320585.txt">Table of n, a(n) for n = 1..10000</a> %p A320585 2,3,5,7,seq(seq(op(select(isprime,[seq(i*10^(d-1)+j,j=1..10^(d-1)-1,2)])),i=[2,3,5,7]),d=1..4); # _Robert Israel_, Apr 02 2020 %t A320585 Select[Range[575], PrimeQ[#] && PrimeQ[IntegerDigits[#][[1]]] &] (* _Amiram Eldar_, Nov 11 2018 *) %o A320585 (PARI) isok(n) = isprime(n) && isprime(digits(n)[1]); \\ _Michel Marcus_, Oct 17 2018 %Y A320585 Intersection of A000040 and A320584 (numbers whose first digit is prime). %K A320585 nonn,base %O A320585 1,1 %A A320585 _Kritsada Moomuang_, Oct 16 2018