A153877 Numbers n such that 5n-1 and 5n+1 are both prime.

6, 12, 30, 36, 48, 54, 84, 114, 120, 132, 162, 204, 210, 246, 258, 264, 324, 390, 426, 462, 468, 510, 546, 558, 594, 600, 624, 660, 666, 672, 678, 708, 786, 804, 810, 846, 852, 930, 960, 1002, 1020, 1056, 1104, 1128, 1170, 1176, 1218, 1254, 1260, 1272

Offset

1,1

Comments

a(n) is an integer multiple of 6. - Alois P. Heinz, Jan 04 2009

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Example

n=6, 5n-1=29, 5n+1=31; n=30, 5n-1=149, 5n+1=151.

Maple

a:= proc(n::posint) option remember; local m; if n=1 then 6 else for m from a(n-1)+6 by 6 while not (isprime(5*m-1) and isprime(5*m+1)) do od; m fi end: seq(a(n), n=1..100); # Alois P. Heinz, Jan 04 2009

Mathematica

Select[Range[0, 100001], PrimeQ[5#-1]&& PrimeQ[5#+1]&] (* Vincenzo Librandi, Jul 31 2012 *)

Prog

(Magma) [ n: n in [0..2000] | IsPrime(5*n-1) and IsPrime(5*n+1)]; // Vincenzo Librandi, Jul 31 2012

Crossrefs

Cf. A153355, A153088.

Sequence in context: A242949 A341637 A143272 * A229491 A263676 A083494

Adjacent sequences: A153874 A153875 A153876 * A153878 A153879 A153880

Keyword

nonn,easy

Author

Vincenzo Librandi, Jan 03 2009

Extensions

Corrected and extended by Alois P. Heinz and R. J. Mathar, Jan 04 2009

Status

approved