|
Search: id:A084700
|
|
|
| A084700 |
|
Smallest k such that k*prime(i)+1 is prime for i = 1 to n. |
|
+0
2
|
|
| 1, 2, 2, 6, 6, 6, 6, 192660, 437286240, 37202202450, 148684126500, 2258581791060, 161082438032880
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
COMMENT
|
For n > 7, a(n) == 0 mod 10.
For n > 7, a(n) == 0 mod 30.
|
|
EXAMPLE
|
a(4) = a(5) = a(6) = a(7) = 6 as 2*6+1 = 13, 3*6+1 = 19, 5*6+1 = 31, 7*6+1 = 43, 11*6+1 = 67, 13*6+1 = 79, 17*6+1 = 103 are all primes.
|
|
MATHEMATICA
|
k = 2; Do[ While[ Union[ PrimeQ[ Table[ k*Prime[i] + 1, {i, 1, n}]]] != {True}, k+=2]; Print[k], {n, 2, 8}]
|
|
CROSSREFS
|
Cf. A084701.
Sequence in context: A086447 A140219 A077081 this_sequence A122766 A033742 A048594
Adjacent sequences: A084697 A084698 A084699 this_sequence A084701 A084702 A084703
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jun 08 2003
|
|
EXTENSIONS
|
Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com) and Don Reble (djr(AT)nk.ca), Jun 15 2003
Terms 11, 12, and 13 found by Phil Carmody using his GenSv generic siever, Mar 08 2004
|
|
|
Search completed in 0.002 seconds
|
