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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

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