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A091180 Primes of the form 3*p - 2 such that p is a prime. 32
7, 13, 19, 31, 37, 67, 109, 127, 139, 157, 181, 199, 211, 307, 337, 379, 409, 487, 499, 541, 571, 577, 631, 751, 769, 787, 811, 829, 877, 919, 937, 991, 1009, 1039, 1117, 1201, 1291, 1297, 1327, 1381, 1399, 1459, 1471, 1567, 1621, 1669, 1759, 1777, 1801 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Mother primes of order 1. - Artur Jasinski, Dec 12 2007
LINKS
FORMULA
a(n) = 3*A088878(n)-2.
EXAMPLE
From K. D. Bajpai, Jun 20 2015: (Start)
a(4) = 31: 3*11 - 2 = 31; A088878(4) = 11.
a(6) = 67: 3*23 - 2 = 67; A088878(6) = 23.
(End)
MAPLE
A091180:= n-> (3*ithprime(n)-2): select(isprime, [seq((A091180(n), n=1..100))]); # K. D. Bajpai, Jun 20 2015
MATHEMATICA
n = 1; a = {}; Do[If[PrimeQ[(Prime[k] + 2n)/(2n + 1)], AppendTo[a, Prime[k]]], {k, 1, 500}]; a (* Artur Jasinski, Dec 12 2007 *)
Select[Table[3*Prime[n] - 2, {n, 1000}], PrimeQ] (* K. D. Bajpai, Jun 20 2015 *)
PROG
(PARI) forprime(p = 1, 1000, k =( 3*p -2); if ( isprime(k), print1(k, ", "))); \\ K. D. Bajpai, Jun 20 2015
(Magma) [ k: p in PrimesUpTo(1000) | IsPrime(k) where k is (3*p-2) ]; // K. D. Bajpai, Jun 20 2015
CROSSREFS
Cf. A136020.
Sequence in context: A081765 A257002 A216567 * A272381 A242190 A053458
KEYWORD
nonn,easy
AUTHOR
Ray Chandler, Dec 27 2003
EXTENSIONS
Name clarified by Jinyuan Wang, Aug 06 2021
STATUS
approved

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Last modified March 2 18:02 EST 2024. Contains 370498 sequences. (Running on oeis4.)