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A156761
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Tribonacci primes that are also primes when their digits are reversed.
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0
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OFFSET
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1,1
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COMMENTS
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This is to A115347 as Fibonacci numbers A000045 are to A000213 tribonacci numbers. Except for palidromatic tribonacci numbers {3, 5, ...} these are tribonacci emirps, A000213 INTERSECTION A006567.
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LINKS
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FORMULA
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EXAMPLE
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a(5) = 1201 because 1201 is prime, and is the 13th tribonacci number A000213(13), and R(1201) = A004086(1201) = 1021 is also prime. a(6) = 128199521 = the 10th tribonacci prime A056816(10), and its digital reverse 125991821 is also prime.
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MATHEMATICA
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Select[LinearRecurrence[{1, 1, 1}, {1, 1, 1}, 200], AllTrue[{#, IntegerReverse[ #]}, PrimeQ]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 31 2019 *)
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CROSSREFS
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KEYWORD
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more,nonn,base
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AUTHOR
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STATUS
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approved
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