|
|
A283236
|
|
Numbers k such that (86*10^k - 329)/9 is prime.
|
|
0
|
|
|
1, 2, 7, 22, 50, 76, 77, 130, 193, 259, 347, 590, 665, 838, 1516, 3512, 3566, 3688, 5393, 5408, 5875, 10160, 24238, 127967
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
For k>1, numbers such that the digit 9 followed by k-2 occurrences of the digit 5 followed by the digits 19 is prime (see Example section).
a(25) > 2*10^5.
|
|
LINKS
|
|
|
EXAMPLE
|
2 is in this sequence because (86*10^2 - 329)/9 = 919 is prime.
Initial terms and primes associated:
a(1) = 1, 59;
a(2) = 2, 919;
a(3) = 7, 95555519;
a(4) = 22, 95555555555555555555519;
a(5) = 50, 955555555555555555555555555555555555555555555555519; etc.
|
|
MATHEMATICA
|
Select[Range[1, 100000], PrimeQ[(86*10^# - 329)/9] &]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more,hard
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|