|
|
A274456
|
|
Numbers k such that 5*10^k + 77 is prime.
|
|
0
|
|
|
1, 2, 3, 4, 6, 8, 19, 27, 37, 56, 66, 136, 148, 387, 534, 536, 1273, 1593, 1796, 2026, 2164, 2502, 6128, 18714, 23327, 25427, 46461, 88182, 88377, 104326, 127153, 135019
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
For k > 1, numbers k such that the digit 5 followed by k-2 occurrences of the digit 0 followed by the digits 77 is prime (see Example section).
a(33) > 2*10^5.
|
|
LINKS
|
|
|
EXAMPLE
|
3 is in this sequence because 5*10^3 + 77 = 5077 is prime.
Initial terms and associated primes:
a(1) = 1, 127;
a(2) = 2, 577;
a(3) = 3, 5077;
a(4) = 4, 50077;
a(5) = 6, 5000077, etc.
|
|
MATHEMATICA
|
Select[Range[0, 100000], PrimeQ[5*10^# + 77] &]
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|