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A032758
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Undulating primes (digits alternate).
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31
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2, 3, 5, 7, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 131, 151, 181, 191, 313, 353, 373, 383, 727, 757, 787, 797, 919, 929, 18181, 32323, 35353, 72727, 74747, 78787, 94949, 95959, 1212121, 1616161, 323232323, 383838383
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OFFSET
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1,1
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COMMENTS
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Sometimes called "smoothly undulating primes", to distinguish them from A059168.
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REFERENCES
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C. A. Pickover, "Keys to Infinity", Wiley 1995, p. 159,160.
C. A. Pickover, "Wonders of Numbers", Oxford New York 2001, Chapter 52, pp. 123-124, 316-317.
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LINKS
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Table of n, a(n) for n=1..51.
C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Zentralblatt review
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MATHEMATICA
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a[n_] := DeleteDuplicates[Take[IntegerDigits[n], {1, -1, 2}]]; b[n_] := DeleteDuplicates[Take[IntegerDigits[n], {2, -1, 2}]]; t={}; Do[p=Prime[n]; If[p<10, AppendTo[t, p], If[Length[a[p]] == Length[b[p]] == 1 && a[p][[1]] != b[p][[1]], AppendTo[t, p]]], {n, 3*10^7}]; t (* Jayanta Basu, May 04 2013 *)
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CROSSREFS
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Cf. A033619, A030291.
Sequence in context: A126058 A050757 A059168 * A106118 A029743 A042990
Adjacent sequences: A032755 A032756 A032757 * A032759 A032760 A032761
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KEYWORD
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nonn,base,easy
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AUTHOR
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Patrick De Geest, May 15, 1998.
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EXTENSIONS
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Sequence corrected by Juri-Stepan Gerasimov, Jan 28 2010
Offset corrected by Arkadiusz Wesolowski, Sep 13 2011
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STATUS
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approved
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