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A252494
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Numbers n such that all prime factors of n and n+1 are <= 11. (Related to the abc conjecture.)
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6
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1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 14, 15, 20, 21, 24, 27, 32, 35, 44, 48, 49, 54, 55, 63, 80, 98, 99, 120, 125, 175, 224, 242, 384, 440, 539, 2400, 3024, 4374, 9800
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OFFSET
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1,2
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COMMENTS
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This sequence is complete by a theorem of Stormer, cf. A002071.
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LINKS
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MATHEMATICA
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Select[Range[10000], FactorInteger[ # (# + 1)][[ -1, 1]] <= 11 &]
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PROG
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(PARI) for(n=1, 9e6, vecmax(factor(n++)[, 1])<12 && vecmax(factor(n--+(n<2))[, 1])<12 && print1(n", ")) \\ Skips 2 if n+1 is not 11-smooth: Twice as fast as the naive version.
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CROSSREFS
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KEYWORD
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nonn,fini,full
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AUTHOR
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STATUS
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approved
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