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 A235618 #14 Nov 02 2023 11:07:31 %S A235618 2,3,11,19,67,89,137,211,523,593,641,659,1097,1163,1627,1667,1747, %T A235618 4177,4673,4691,5323,5657,5659,5779,5827,5849,8209,8387,8779,8849, %U A235618 9227,9241,9283,9433,9803,9817,9859,9883,9929,12289,12377,12433,12491,12953,13003,13331,13339,13441 %N A235618 Primes whose base-8 representation also is the base-4 representation of a prime. %C A235618 This sequence is part of the two-dimensional array of sequences 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. %H A235618 Robert Price, <a href="/A235618/b235618.txt">Table of n, a(n) for n = 1..1627</a> %H A235618 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 A235618 E.g., 11 = 13_8 and 13_4 = 7 are both prime. %o A235618 (PARI) is(p,b=4,c=8)=vecmax(d=digits(p,c))<b&&isprime(vector(#d,i,b^(#d-i))*d~)&&isprime(p) %o A235618 (PARI) forprime(p=1,3e3,is(p,8,4)&&print1(vector(#d=digits(p,4),i,8^(#d-i))*d~,",")) \\ To produce the terms, this is more efficient than to select them using straightforwardly is(.)=is(.,4,9) %Y A235618 Cf. A235633, A235265, A235266, A152079, A235461 - A235482, A065720 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235615 - A235639. See the LINK for further cross-references. %K A235618 nonn,base %O A235618 1,1 %A A235618 _M. F. Hasler_, Jan 13 2014