|
|
A273783
|
|
Numbers k such that (86*10^k - 77)/9 is prime.
|
|
0
|
|
|
2, 3, 8, 9, 12, 14, 27, 32, 50, 80, 98, 99, 194, 237, 338, 828, 830, 1265, 2583, 3639, 5232, 5940, 9371, 10268, 13424, 26975, 36147, 60165, 69260, 93263
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
For k>1, numbers n such that the digit 9 followed by k-2 occurrences of the digit 5 followed by the digits 47 is prime (see Example section).
a(31) > 2*10^5.
|
|
LINKS
|
|
|
EXAMPLE
|
3 is in this sequence because (86*10^3 - 77)/9 = 9547 is prime.
Initial terms and primes associated:
a(1) = 2, 947;
a(2) = 3, 9547;
a(3) = 8, 955555547;
a(4) = 9, 9555555547;
a(5) = 12, 9555555555547, etc.
|
|
MATHEMATICA
|
Select[Range[0, 100000], PrimeQ[(86*10^# - 77)/9] &]
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|