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Search: id:A002071
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| A002071 |
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Number of pairs of consecutive integers x, x+1 such that all prime factors of both x and x+1 are at most the n-th prime.
(Formerly M3386 N1366)
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+0
9
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| 1, 4, 10, 23, 40, 68, 108, 167, 241, 345, 482, 653, 869, 1153, 1502
(list; graph; listen)
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OFFSET
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1,2
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
E. F. Ecklund and R. B. Eggleton, Prime factors of consecutive integers, Amer. Math. Monthly, 79 (1972), 1082-1089.
D. H. Lehmer, On a problem of Stormer, Ill. J. Math., 8 (1964), 57-69.
Stormer, Carl (1897). "Quelques theoremes sur l'equation de Pell x^2 - Dy^2 = +-1 et leurs applications". Skrifter Videnskabs-selskabet (Christiania), Mat.-Naturv. Kl. I (2).
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LINKS
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D. Eppstein, Smooth pairs.
D. Eppstein, Maple program
Wikipedia, Stormer's theorem
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CROSSREFS
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Cf. A002072.
Cf. A138180 (triangle of x values for each n).
A145604, A145605, A145606 [From T. D. Noe (noe(AT)sspectra.com), Oct 16 2008]
Sequence in context: A023378 A038423 A109293 this_sequence A024980 A002766 A008268
Adjacent sequences: A002068 A002069 A002070 this_sequence A002072 A002073 A002074
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KEYWORD
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nonn,nice,more
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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Better description and more terms from David Eppstein (eppstein(AT)ics.uci.edu), Mar 23 2007
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