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 A065727 #25 Dec 05 2024 19:12:23 %S A065727 2,3,5,7,37,43,61,109,127,199,271,277,379,457,487,523,541,613,619,673, %T A065727 727,757,883,907,919,991,997,1033,1117,1249,1447,1483,1531,1549,1567, %U A065727 1627,1693,1699,1747,1753,1987,2053,2161,2221,2287,2341,2347,2437,2473 %N A065727 Primes p such that the decimal expansion of its base-9 conversion is also prime. %C A065727 In general rebase notation (Marc LeBrun): p9 = (9) [p] (10). %H A065727 Harry J. Smith, <a href="/A065727/b065727.txt">Table of n, a(n) for n = 1..1000</a> %e A065727 E.g., 997_10 = 1327_9 is prime, and so is 1327_10. %t A065727 Select[ Range[2500], PrimeQ[ # ] && PrimeQ[ FromDigits[ IntegerDigits[ #, 9]]] & ] %t A065727 NestList[NestWhile[NextPrime, #, ! PrimeQ[FromDigits[IntegerDigits[#2, 9]]] &, 2] &, 2, 48] (* _Jan Mangaldan_, Jul 01 2020 *) %t A065727 Select[Prime[Range[400]],PrimeQ[FromDigits[IntegerDigits[#,9],10]]&] (* _Harvey P. Dale_, Sep 19 2021 *) %o A065727 (PARI) isok(p) = isprime(p) && isprime(fromdigits(digits(p, 9))); \\ _Michel Marcus_, Jul 02 2020 %Y A065727 Cf. A065720, A065721, A065722, A065723, A065724, A065725, A065726, A065361. %Y A065727 Intersection of A000040 and A036964. %K A065727 nonn,base %O A065727 1,1 %A A065727 _Patrick De Geest_, Nov 15 2001