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A295124 a(n) = smallest number k with n prime factors such that 2d + k/d is prime for every d | k. 2
1, 3, 15, 105, 93081 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Such k must be an odd squarefree number.

a(n) has 2^n divisors and each gives another prime.

Conjecture: the sequence is infinite. It is hard to believe!

a(n) is the smallest k such that A088627(k) = A000005(k) = 2^n.

LINKS

Table of n, a(n) for n=0..4.

FORMULA

a(n) = A293756(n+1)/2.

CROSSREFS

Cf. A088627, A293756.

Subsequence of A244520 (2d + k/d is prime for every d|k).

Sequence in context: A231634 A353587 A128276 * A107878 A218688 A120016

Adjacent sequences:  A295121 A295122 A295123 * A295125 A295126 A295127

KEYWORD

nonn,more

AUTHOR

Thomas Ordowski, Nov 15 2017

EXTENSIONS

a(4) from Michel Marcus, Nov 15 2017

STATUS

approved

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Last modified May 19 18:35 EDT 2022. Contains 353847 sequences. (Running on oeis4.)