A295124 - OEIS

A295124

a(n) = smallest number k with n prime factors such that 2d + k/d is prime for every d | k.

1, 3, 15, 105, 93081

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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

FORMULA

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

CROSSREFS

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

KEYWORD

nonn,more

AUTHOR

EXTENSIONS

a(4) from Michel Marcus, Nov 15 2017

STATUS

approved