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Search: id:A077784
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| A077784 |
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Palindromic wing primes (a.k.a. near-repdigit palindromes) of the form (10^a(n)-1)/3+2*10^[ a(n)/2 ]. |
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+0
1
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| 3, 5, 35, 159, 237, 325, 355, 371, 481, 1649, 3641, 4709
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Prime versus probable prime status and proofs are given in the author's table.
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REFERENCES
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C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
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LINKS
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Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's)
Makoto Kamada, Factorizations of 33...33533...33
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EXAMPLE
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a(n)=5 -> (10^5-1)/3+2*10^2 = 33533.
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MATHEMATICA
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Do[ If[ PrimeQ[(10^n + 6*10^Floor[n/2] - 1)/3], Print[n]], {n, 3, 4800, 2}] (from Robert G. Wilson v (rgwv(at)rgwv.com), Dec 16 2005)
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CROSSREFS
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Partial sums of S(n, x), for x=1...9: A021823, A000217, A027941, A061278, A089817, A053142, A092521, A076765, A092420.
Cf. A004023, A077775-A077798, A107123-A107127, A107648, A107649, A114633-A114647.
Sequence in context: A001790 A057908 A120828 this_sequence A145640 A086158 A158878
Adjacent sequences: A077781 A077782 A077783 this_sequence A077785 A077786 A077787
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KEYWORD
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nonn
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AUTHOR
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Patrick De Geest (pdg(AT)worldofnumbers.com), Nov 16 2002.
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