The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A104163 Primes p such that (2p+1)/3 is prime. 5
 7, 19, 43, 61, 79, 109, 151, 163, 223, 271, 349, 421, 439, 523, 601, 613, 631, 673, 691, 811, 853, 919, 991, 1009, 1051, 1063, 1153, 1213, 1231, 1279, 1321, 1429, 1531, 1549, 1663, 1693, 1789, 1801, 1873, 1933, 1951, 2113, 2143, 2179, 2221, 2239, 2503, 2539 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Dickson's conjecture implies that this sequence is infinite. - Charles R Greathouse IV, Jul 31 2012 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 FORMULA a(n)=(3*A158708(n+1)-1)/2 Zak Seidov, Jul 31 2012 EXAMPLE 7 is in the sequence because (2 * 7 + 1)/3 = 5, which is also prime. 19 is in the sequence because (2 * 19 + 1)/3 = 13, which is also prime. MATHEMATICA Select[Range[7, 2539, 2], PrimeQ[#] && PrimeQ[(2# + 1)/3]&] (* Zak Seidov, Jul 31 2012 *) Select[Prime[Range[400]], PrimeQ[(2 # + 1) / 3]&] (* Vincenzo Librandi, Apr 14 2013 *) PROG (PARI) is(n)=n%3==1 && isprime((2*n+1)/3) && isprime(n) \\ Charles R Greathouse IV, Jul 31 2012 CROSSREFS Cf. A005384. Sequence in context: A225279 A192755 A141193 * A145993 A265676 A054690 Adjacent sequences: A104160 A104161 A104162 * A104164 A104165 A104166 KEYWORD nonn,easy AUTHOR Roger L. Bagula, Mar 10 2005 EXTENSIONS New name from Charles R Greathouse IV, Jul 31 2012 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 22 17:00 EDT 2024. Contains 372758 sequences. (Running on oeis4.)