The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A137906 Least k such that k*(2^p-1)*(k*(2^p-1)-1)-1 is prime, where 2^p-1 runs through the Mersenne primes. 3
 1, 1, 1, 1, 1, 4, 1, 27, 14, 34, 6, 132, 97, 1, 500, 1816, 1292, 136, 2445, 15, 1934, 5472, 1584, 2734, 21022, 5870 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS EXAMPLE 1*(2^2-1)*(1*(2^2-1)-1)-1=5 prime, 2^2-1 first Mersenne prime, a(1)=1; 1*(2^3-1)*(1*(2^3-1)-1)-1=41 prime, 2^3-1 second Mersenne prime, a(2)=1. CROSSREFS Cf. A137907, A137908, A137909. Sequence in context: A095891 A095887 A225213 * A139051 A061692 A096206 Adjacent sequences:  A137903 A137904 A137905 * A137907 A137908 A137909 KEYWORD nonn,hard,more AUTHOR Pierre CAMI, Feb 22 2008 STATUS approved

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

Last modified July 26 10:48 EDT 2021. Contains 346294 sequences. (Running on oeis4.)