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%I A235482 #16 Jan 16 2022 23:26:34
%S A235482 2,3,7,11,17,19,37,41,61,67,71,97,109,131,139,149,151,157,167,191,197,
%T A235482 211,251,269,281,337,349,367,401,409,439,449,457,467,487,491,499,521,
%U A235482 557,569,607,619,631,647,661,739,761,769,821,829,887,907,941,947,967,1009,1019,1031,1061,1069,1087
%N A235482 Primes whose base-5 representation is also the base-9 representation of a prime.
%C A235482 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 A235482 A subsequence of A197636 and of course of A000040 ⊂ A015919.
%H A235482 Giovanni Resta, <a href="/A235482/b235482.txt">Table of n, a(n) for n = 1..10000</a>
%H A235482 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 A235482 41 = 131_5 and 131_9 = 109 are both prime, so 41 is a term.
%t A235482 Select[Prime@ Range@ 500, PrimeQ@ FromDigits[ IntegerDigits[#, 5], 9] &] (* _Giovanni Resta_, Sep 12 2019 *)
%o A235482 (PARI) is(p,b=9,c=5)=isprime(vector(#d=digits(p,c),i,b^(#d-i))*d~)&&isprime(p) \\ Note: Code only valid for b > c.
%Y A235482 Cf. A235265, A235266, A235461 - A235481, A065720 ⊂ A036952, A065721 - A065727, A089971 ⊂ A020449, A089981, A090707 - A091924, A235394, A235395. See the LINK for further cross-references.
%K A235482 nonn,base
%O A235482 1,1
%A A235482 _M. F. Hasler_, Jan 12 2014

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