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 A235628 #13 Nov 02 2023 11:07:28 %S A235628 2,3,17,19,73,89,131,163,257,521,577,739,1097,1171,1283,1601,1747, %T A235628 2081,2083,2137,2267,4177,4289,4363,4643,5273,5387,5651,5779,5849, %U A235628 5851,5923,6211,6299,6337,8353,8713,8803,8929,8969,8971,9377,9419,9473,9491,9811,9883,10009 %N A235628 Primes whose base-8 representation also is the base-5 representation of a prime. %C A235628 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 A235628 Robert Price, <a href="/A235628/b235628.txt">Table of n, a(n) for n = 1..3395</a> %H A235628 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 A235628 Both 17 = 23_8 and 23_5 = 13 are prime. %o A235628 (PARI) is(p,b=5,c=8)=vecmax(d=digits(p,c))<b&&isprime(vector(#d,i,b^(#d-i))*d~)&&isprime(p) %o A235628 (PARI) forprime(p=1,3e3,is(p,8,5)&&print1(vector(#d=digits(p,5),i,8^(#d-i))*d~,",")) \\ To produce the terms, this is more efficient than to select them using straightforwardly is(.)=is(.,5,8) %Y A235628 Cf. A235632, A235265, A235266, A152079, A235461 - A235482, A065720 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235615 - A235639. See the LINK for further cross-references. %K A235628 nonn,base %O A235628 1,1 %A A235628 _M. F. Hasler_, Jan 13 2014