|
| |
|
|
A098959
|
|
Numbers n such that 2*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
|
|
2
| |
|
|
1, 2, 3, 5, 6, 7, 11, 21, 30, 68, 73, 169, 176, 345, 823, 1021, 1191, 2073, 2755, 10717, 14673, 16754, 17606
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
COMMENTS
| Also numbers n such that (8*10^n-11)/3 is prime.
|
|
|
LINKS
| Makoto Kamada, Factorizations of 266...663.
Index entries for primes involving repunits.
|
|
|
EXAMPLE
| For n = 1, 2, 3, 5, 6, 7, we get 23, 263, 2663, 266663, 2666663 and
26666663 which are primes.
|
|
|
MATHEMATICA
| Do[ If[ PrimeQ[(8*10^n - 11)/3], Print[n]], {n, 0, 10000}]
|
|
|
CROSSREFS
| Sequence in context: A019438 A023798 A062084 * A071251 A077571 A101730
Adjacent sequences: A098956 A098957 A098958 * A098960 A098961 A098962
|
|
|
KEYWORD
| more,nonn
|
|
|
AUTHOR
| Julien Peter Benney (jpbenney(AT)ftml.net), Oct 21 2004
|
|
|
EXTENSIONS
| a(15), a(16) & a(17) from Ray Chandler (rayjchandler(AT)sbcglobal.net), Nov 04 2004
a(18) & a(19) from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 17 2004
a(20)-a(23) from Kamada link by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
|
| |
|
|
