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

 Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A153877 Numbers n such that 5n-1 and 5n+1 are both prime. 1
 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 (list; graph; refs; listen; history; text; internal format)
 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: A124679 A242949 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

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 November 24 20:34 EST 2020. Contains 338616 sequences. (Running on oeis4.)