|
Search: id:A118479
|
|
|
| A118479 |
|
Least n-digit prime which is also a twin prime and Sophie Germain prime. |
|
+0
3
|
|
| 3, 11, 179, 1019, 10091, 100361, 1000211, 10001399, 100001651, 1000002359, 10000003001, 100000026569, 1000000000061, 10000000019759, 100000000018109, 1000000000029911, 10000000000013741, 100000000000004381
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
3 and 5 twin primes and 2*3+1=7 prime, so 3 is first of twin primes and Sophie Germain prime, least prime like this of one digit, so a(1)=3
11 and 13 twin primes ans 2*11+1=23 prime, so 11 first of twin primes and Sophie Germain prime, least prime like this with two digits, so a(2)=11
|
|
MATHEMATICA
|
f[n_] := Block[{k = 10^(n - 1)}, While[ !PrimeQ[k] || !PrimeQ[k + 2] || !PrimeQ[2k + 1], k++ ]; k]; Array[f, 18] (* Robert G. Wilson v *)
|
|
CROSSREFS
|
Sequence in context: A006485 A003115 A053888 this_sequence A103836 A081484 A125738
Adjacent sequences: A118476 A118477 A118478 this_sequence A118480 A118481 A118482
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Pierre CAMI (pierrecami(AT)tele2.fr), May 05 2006
|
|
EXTENSIONS
|
Edited by Robert G. Wilson v (rgwv(at)rgwv.com), May 13 2006
|
|
|
Search completed in 0.002 seconds
|
