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A152843 Numbers n such that both 2n+3 and 4n+7 are prime. 2
0, 1, 4, 10, 13, 19, 25, 40, 43, 55, 64, 85, 88, 94, 115, 118, 124, 139, 145, 178, 208, 214, 220, 244, 253, 295, 319, 325, 328, 340, 358, 370, 379, 403, 454, 475, 505, 508, 514, 523, 550, 610, 613, 643, 703, 718, 724, 739, 748, 754, 778, 790, 799, 865, 904, 943 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Or, numbers n such that 2n+3 is a Sophie Germain prime. [Klaus Brockhaus, Dec 22 2008]

LINKS

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

EXAMPLE

For n = 10, 2*n+3 = 23 is prime and 4*n+7 = 47 is prime. 23 = A005384(5).

MATHEMATICA

Join[{0}, Select[Range[1000], PrimeQ[2*#+3] && PrimeQ[4*#+7] &]] (* Vincenzo Librandi, Aug 30 2012 *)

Select[Range[0, 1000], AllTrue[{2#+3, 4#+7}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Aug 07 2015 *)

PROG

(MAGMA) [ n: n in [0..1000] | IsPrime(2*n+3) and IsPrime(4*n+7) ];

CROSSREFS

Cf. A067076 (2n+3 is prime), A089986 (4n+7 is prime), A005384 (Sophie Germain primes).

Sequence in context: A310358 A143804 A342742 * A139121 A310359 A079932

Adjacent sequences:  A152840 A152841 A152842 * A152844 A152845 A152846

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Dec 14 2008

EXTENSIONS

Edited and extended by Klaus Brockhaus, Dec 22 2008

STATUS

approved

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Last modified June 18 20:04 EDT 2021. Contains 345121 sequences. (Running on oeis4.)