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A108144 Numbers n such that (n-1)/P(n-1) is a power of two > 1, where P(n) is the largest prime factor of n. 0
5, 7, 9, 11, 13, 15, 17, 21, 23, 25, 27, 29, 33, 35, 39, 41, 45, 47, 49, 53, 57, 59, 63, 65, 69, 75, 77, 81, 83, 87, 89, 93, 95, 97, 105, 107, 113, 117, 119, 123, 125, 129, 135, 137, 143, 147, 149, 153, 159, 161, 165, 167, 173, 177, 179, 185, 189, 193, 195, 203, 207 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: There are infinitely many primes and semiprimes in this sequence.

LINKS

Table of n, a(n) for n=1..61.

EXAMPLE

1537 is a term because 1536/3 = 512 = 2^9.

CROSSREFS

Cf. A052126.

Sequence in context: A062545 A020735 A329391 * A241835 A279914 A123910

Adjacent sequences:  A108141 A108142 A108143 * A108145 A108146 A108147

KEYWORD

easy,nonn

AUTHOR

Jason Earls, Jul 23 2005

STATUS

approved

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Last modified January 29 04:46 EST 2020. Contains 331335 sequences. (Running on oeis4.)