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!)
 A112229 Table of the smallest (x,y) pairs such that x*n+1 is prime, y*n+1 is a larger prime, and (x*n+1)*(y*n+1)-2 is also prime. 1
 2, 4, 1, 2, 2, 4, 1, 4, 2, 8, 1, 2, 4, 28, 2, 11, 2, 4, 1, 4, 2, 32, 1, 3, 4, 40, 2, 14, 2, 4, 1, 37, 6, 138, 1, 2, 10, 40, 2, 5, 2, 16, 1, 16, 2, 26, 3, 4, 4, 10, 2, 20, 4, 10, 1, 7, 2, 50, 1, 2, 10, 22, 3, 6, 2, 6, 3, 69, 2, 8, 1, 2, 4, 40, 5, 20, 2, 4, 1, 7, 2, 20, 1, 8, 4, 10, 2, 32, 4, 12, 1, 13 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The associated (x*n+1)*(y*n+1) for a solution is a semiprime, so the (x*n+1)*(y*n+1)-2 are actually Chen primes. If more than one pair exists for a given n, priority is given to minimize x, the smaller prime. LINKS EXAMPLE For n=3, (x,y)=(2,4), 2*3+1=7 is prime, 4*3+1=13 is prime, and 7*13-2=89 is a Chen prime. 2,4; 1,2; 2,4; 1,4; 2,8; 1,2; 4,28; 2,11; 2,4; 1,4; 2,32; 1,3; 4,40;... CROSSREFS Cf. A112230. Sequence in context: A305717 A208645 A054708 * A087419 A338095 A050979 Adjacent sequences:  A112226 A112227 A112228 * A112230 A112231 A112232 KEYWORD nonn,tabf AUTHOR Pierre CAMI, Aug 29 2005 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 May 7 19:23 EDT 2021. Contains 343652 sequences. (Running on oeis4.)