|
|
A178321
|
|
Numbers n such that 58/111*(10^(3n)-1)-1 is prime.
|
|
2
|
|
|
1, 2, 15, 74, 278, 541, 668, 1320, 1780, 1874, 4824, 13310, 20420, 24887
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
If n is in the sequence then m=3*(58/111*(10^(3n)-1)-1)) is a term of A072394.
Namely if n is a term of this sequence then for m=1/37*(58*10^(3n)-169) we have sigma(m)=reversal(m)-m (see comment lines of A072394).
There is no further term up to 3000. Numbers corresponding to the larger terms are probable primes.
|
|
LINKS
|
|
|
MATHEMATICA
|
Do[If[PrimeQ[58/111*(10^(3 n) - 1) - 1], Print[n]], {n, 1874}]
|
|
CROSSREFS
|
|
|
KEYWORD
|
more,nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|