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A235616
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Primes whose base-6 representation also is the base-4 representation of a prime.
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3
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2, 3, 7, 19, 37, 79, 127, 229, 307, 487, 523, 547, 727, 733, 757, 1297, 1423, 1549, 1567, 1627, 1747, 1777, 2647, 2683, 2713, 2857, 2887, 3067, 3361, 3889, 3943, 4003, 4153, 4441, 4651, 4663, 7789, 7867, 8209, 8263, 8293, 8317, 8443, 8467, 9109, 9157, 9343, 9547, 9733
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OFFSET
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1,1
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COMMENTS
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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.
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LINKS
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EXAMPLE
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E.g., 7 = 11_6 and 11_4 = 5 are both prime.
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PROG
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(PARI) is(p, b=4, c=6)=vecmax(d=digits(p, c))<b&&isprime(vector(#d, i, b^(#d-i))*d~)&&isprime(p)
(PARI) forprime(p=1, 3e3, is(p, 6, 4)&&print1(vector(#d=digits(p, 4), i, 6^(#d-i))*d~, ", ")) \\ To produce the terms, this is more efficient than to select them using straightforwardly is(.)=is(., 4, 6)
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CROSSREFS
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Cf. A235624, A235265, A235266, A152079, A235461 - A235482, A065720 - A065727, A235394, A235395, A089971 ⊂ A020449, A089981, A090707 - A091924, A235615 - A235639. See the LINK for further cross-references.
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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