|
|
A288482
|
|
Numbers k such that (77*10^k - 293)/9 is prime.
|
|
0
|
|
|
1, 2, 4, 7, 10, 11, 29, 35, 52, 56, 106, 217, 580, 673, 808, 1354, 1666, 3292, 3770, 8989, 16525, 24773, 39301, 125330, 158407
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
For k>1, numbers such that the digit 8 followed by k-2 occurrences of the digit 5 followed by the digits 23 is prime (see Example section).
a(26) > 2*10^5.
|
|
LINKS
|
|
|
EXAMPLE
|
4 is in this sequence because (77*10^4 - 293)/9 = 85523 is prime.
Initial terms and primes associated:
a(1) = 1, 53;
a(2) = 2, 823;
a(3) = 4, 85523;
a(4) = 7, 85555523;
a(5) = 10, 85555555523; etc.
|
|
MATHEMATICA
|
Select[Range[1, 100000], PrimeQ[(77*10^# - 293)/9] &]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more,hard
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|