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 A065721 #20 Dec 05 2024 19:12:19 %S A065721 2,67,79,103,139,157,181,193,199,211,229,277,283,307,313,349,367,373, %T A065721 409,421,433,439,463,523,541,547,571,577,751,829,883,919,1021,1033, %U A065721 1039,1087,1171,1249,1303,1429,1483,1579,1597,1621,1741,1783,1789,1873 %N A065721 Primes p whose base-3 expansion is also the decimal expansion of a prime. %C A065721 In general rebase notation (Marc LeBrun): p3 = (3) [p] (10). %H A065721 Harry J. Smith, <a href="/A065721/b065721.txt">Table of n, a(n) for n = 1..1000</a> %H A065721 M. F. Hasler, <a href="https://docs.google.com/document/d/10IM7fcAbB2tqRGuwfGvuEGUzD_IXbgXPDK0tfxN4M3o/pub">Primes whose base c expansion is also the base b expansion of a prime</a> %e A065721 1033_10 = 1102021_3 is prime, and so is 1102021_10. %t A065721 Select[ Range[1900], PrimeQ[ # ] && PrimeQ[ FromDigits[ IntegerDigits[ #, 3]]] & ] %o A065721 (PARI) is(p,b=10,c=3)=isprime(vector(#c=digits(p,c),i,b^(#c-i))*c~)&&isprime(p) \\ _M. F. Hasler_, Jan 12 2014 %Y A065721 Primes in A036954. %Y A065721 Cf. A065720 up to A065727, A065361. See the Links for further cross-references. %K A065721 nonn,base %O A065721 1,1 %A A065721 _Patrick De Geest_, Nov 15 2001 %E A065721 Definition clarified by _M. F. Hasler_, Jan 12 2014