|
| |
|
|
A096507
|
|
Numbers n such that 6*R_n + 1 is a prime, where R_n = 11...1 is the repunit (A002275) of length n.
|
|
10
| |
|
|
1, 2, 6, 8, 9, 11, 20, 23, 41, 63, 66, 119, 122, 149, 252, 284, 305, 592, 746, 875, 1204, 1364, 2240, 2403, 5106, 5776, 5813, 12456, 14235
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Also numbers n such that (2*10^n+1)/3 is prime.
No others less than 25557. These numbers form a near-repdigit sequence (6)w7.
All the terms from n = 2403 through 14235 correspond to primes. Joao da Silva (zxawyh66(AT)yahoo.com), Oct 3 2005
|
|
|
LINKS
| Makoto Kamada, Factorizations of 66...667.
Index entries for primes involving repunits
|
|
|
EXAMPLE
| n = 9 gives 2000000001/3 = 666666667, which is prime.
n=20 means that 66666666666666666667 is a prime number.
|
|
|
CROSSREFS
| Equals A056657 + 1.
Cf. A096503, A096504, A096505, A096506, A096507, A096508.
Sequence in context: A174331 A043341 A023714 * A050675 A034591 A047278
Adjacent sequences: A096504 A096505 A096506 * A096508 A096509 A096510
|
|
|
KEYWORD
| base,nonn
|
|
|
AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Jul 12 2004
|
|
|
EXTENSIONS
| More terms from Julien Peter Benney (jpbenney(AT)ftml.net), Sep 14 2004
|
| |
|
|
