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A292114
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List of numbers n such that A039655(n) reaches a new record high.
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4
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2, 4, 9, 121, 301, 441, 468, 3171, 8373, 13440, 16641, 16804, 83161, 100652, 133200, 367428, 395640, 459680, 701823, 3739690, 4238314, 6698616, 9014248, 12301860, 16956850, 22230514, 54889200, 60676144, 84983056, 116648892, 128942664
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OFFSET
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1,1
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COMMENTS
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Naively, one might have expected these numbers to have some other distinguishing property (primorials, perhaps), but that seems not to be the case.
Increasingly many of the values are of the form m*p with a (large) prime p and a smooth m, often m = 2^k (for a(n), n = 12, 14, 21, 23, 26, 28, 29, ...) or m = 2^k*3^k' (n = 7, 9, 19, 22, 30, ...) or m = 2^k*5^k' (n = 20, 25, ...). I conjecture that almost all terms are even. Also, for most terms (n = 1, 2, 3, 4, 5, 7, 10, 12, 14, 15, 16, 17, 19, 20, 21, 23, 24, 25, 26, 29, 30, 31, ...), either a(n)-1 or a(n)+1 has at most 2 prime divisors. - M. F. Hasler, Sep 25 2017
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LINKS
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N. J. A. Sloane, Three (No, 8) Lovely Problems from the OEIS, Experimental Mathematics Seminar, Rutgers University, Oct 05 2017, Part I, Part 2, Slides. (Mentions this sequence)
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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