The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

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