|
| |
|
|
A103099
|
|
Numbers n such that 9*10^n + 4*R_n + 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
|
|
1
|
|
|
|
1, 2, 4, 25, 58, 148, 373, 421, 1915, 3746, 16784, 30050, 60026, 93346
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
COMMENTS
|
Also numbers n such that (85*10^n+23)/9 is prime.
a(15) > 10^5. - Robert Price, Nov 14 2015
|
|
|
LINKS
|
Table of n, a(n) for n=1..14.
Makoto Kamada, Prime numbers of the form 944...447.
Index entries for primes involving repunits.
|
|
|
FORMULA
|
a(n) = A101008(n) + 1.
|
|
|
MATHEMATICA
|
Do[ If[ PrimeQ[(85*10^n + 23)/9], Print[n]], {n, 0, 10000}]
|
|
|
PROG
|
(PARI) is(n)=isprime(9*10^n + 4*(10^n-1)/9 + 3) \\ Anders Hellström, Nov 14 2015
|
|
|
CROSSREFS
|
Cf. A002275, A101008.
Sequence in context: A128299 A143672 A001510 * A342665 A266495 A119029
Adjacent sequences: A103096 A103097 A103098 * A103100 A103101 A103102
|
|
|
KEYWORD
|
more,nonn
|
|
|
AUTHOR
|
Robert G. Wilson v, Jan 19 2005
|
|
|
EXTENSIONS
|
a(11) from Kamada data by Robert Price, Dec 14 2010
a(12) from Erik Branger May 01 2013 by Ray Chandler, Aug 17 2013
a(13)-a(14) from Robert Price, Nov 14 2015
|
|
|
STATUS
|
approved
|
| |
|
|
