|
| |
|
|
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 *)
|
|
|
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: A103568 A087444 A143804 * A139121 A079932 A191107
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
|
| |
|
|
