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A292114
List of numbers n such that A039655(n) reaches a new record high.
4
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
OFFSET
1,1
COMMENTS
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
LINKS
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)
PROG
(PARI) m=-n=1; until(print1(n", "), until(A039655(n++)>m, ); m=A039655(n)) \\ M. F. Hasler, Sep 25 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Sep 22 2017
EXTENSIONS
More terms from Hugo Pfoertner, Sep 22 2017
STATUS
approved