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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
| 1,1
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COMMENTS
| 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.
The next term, if it exists, is greater than A000213(10000). [From Dmitry Kamenetsky (dkamen(AT)rsise.anu.edu.au), Mar 03 2009]
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FORMULA
| {p such that p is in A000040 and p is in A000213 and R(p) = A004086(p) is in A000040} = {p such that p is in A056816 and R(p) = is in A000040}.
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EXAMPLE
| 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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CROSSREFS
| Cf. A000040, A000045, A000213, A004086, A006567, A056816, A115347.
Sequence in context: A103149 A007802 A056816 * A151261 A148504 A148505
Adjacent sequences: A156758 A156759 A156760 * A156762 A156763 A156764
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KEYWORD
| more,nonn,base
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AUTHOR
| Jonathan Vos Post (jvospost3(AT)gmail.com), Feb 15 2009
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