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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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1
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3, 5, 35, 159, 237, 325, 355, 371, 481, 1649, 3641, 4709
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Prime versus probable prime status and proofs are given in the author's table.
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REFERENCES
| C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
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LINKS
| Patrick De Geest, World!Of Numbers, Palindromic Wing Primes (PWP's)
Makoto Kamada, Prime numbers of the form 33...33533...33
Index entries for primes involving repunits.
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FORMULA
| a(n) = 2*A183175(n)+1.
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EXAMPLE
| a(n)=5 -> (10^5-1)/3+2*10^2 = 33533.
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MATHEMATICA
| 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
| 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, A115073, A183174-A183187.
Sequence in context: A173092 A057908 A120828 * A145640 A086158 A158878
Adjacent sequences: A077781 A077782 A077783 * A077785 A077786 A077787
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KEYWORD
| more,nonn,base
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AUTHOR
| Patrick De Geest (pdg(AT)worldofnumbers.com), Nov 16 2002.
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