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A114835
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Minimal set of palindrome prime-strings in base 10 in the sense of A071062.
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3
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2, 3, 5, 7, 11, 919, 94049, 94649, 94849, 94949, 96469, 98689, 9809089, 9888889, 9889889, 9908099, 9980899, 9989899, 900808009, 906686609, 906989609, 908000809, 908444809, 908808809, 909848909, 960898069, 968999869, 988000889
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OFFSET
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1,1
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COMMENTS
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The one-digit primes are palindrome by default so the sequence starts off 2, 3, 5, 7 and so from now on all primes fitting one of the patterns *2*, *3*, *5*, *7* are excluded. The first palindrome prime that is not excluded is 11 so our list is now 2, 3, 5, 7, 11. Observe that from now on all the only palindrome primes allowed have first and last digit 9 and the only middle digits allowed are then 0, 1, 4, 6, 8, 9. But the first and only 3 digit palindrome to occur is 919, so from now on the only middle digits allowed are 0, 4, 6, 8, 9. The five digit palindrome primes that do not fit the patterns *2*, *3*, *5*, *7*, *1*1* and *9*1*9* are 94049, 94649, 94849, 94949, 96469, 98689. The rest of the sequence is determined in this recursive manner.
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REFERENCES
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J.-P. Delahaye, "Pour la science", (French edition of Scientific American), Juin 2002, p. 99.
J. Shallit, Minimal primes, J. Recreational Mathematics, vol. 30.2, pp. 113-117, 1999-2000.
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LINKS
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J. Shallit, Minimal primes, J. Recreational Mathematics, vol. 30.2, pp. 113-117, 1999-2000.
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EXAMPLE
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a(6)=919 since it is the first 3-digit palindrome prime that does not fit the wildcard pattern established by the previous 5 elements, 2, 3, 5, 7, 11.
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MAPLE
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Maple worksheet available upon request.
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CROSSREFS
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KEYWORD
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base,fini,full,nonn
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AUTHOR
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STATUS
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approved
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