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 A235473 #19 Jan 16 2022 23:30:51 %S A235473 2,43,61,67,97,103,127,139,151,157,199,211,229,277,283,331,337,349, %T A235473 373,379,433,439,463,499,523,571,601,607,727,751,787,823,853,883,919, %U A235473 991,1063,1087,1117,1213,1249,1327,1381,1429,1483,1531,1567,1597,1627,1759,1783,1867,1999 %N A235473 Primes whose base-3 representation is also the base-4 representation of a prime. %C A235473 This sequence is part of a two-dimensional array of sequences, given in the LINK, based on this same idea for any two different bases b, c > 1. Sequence A235265 and A235266 are the most elementary ones in this list. Sequences A089971, A089981 and A090707 through A090721, and sequences A065720 - A065727, follow the same idea with one base equal to 10. %C A235473 This is a subsequence of A045331 and A045375. %H A235473 Harvey P. Dale, <a href="/A235473/b235473.txt">Table of n, a(n) for n = 1..1000</a> %H A235473 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 A235473 43 = 1121_3 and 1121_4 = 89 are both prime, so 43 is a term. %t A235473 Select[Prime[Range[400]],PrimeQ[FromDigits[IntegerDigits[#,3],4]]&] (* _Harvey P. Dale_, Oct 16 2015 *) %o A235473 (PARI) is(p,b=4,c=3)=isprime(vector(#d=digits(p,c),i,b^(#d-i))*d~)&&isprime(p) \\ Note: This code is only valid for b > c. %Y A235473 Cf. A235266, A235474, A152079, A235475 - A235479, A065720 ⊂ A036952, A065721 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235461 - A235482. See the LINK for further cross-references. %K A235473 nonn,base %O A235473 1,1 %A A235473 _M. F. Hasler_, Jan 12 2014