|
| |
|
|
A032619
|
|
Numbers k such that k concatenated with k+4 is a prime.
|
|
3
|
|
|
|
3, 5, 17, 27, 35, 39, 45, 47, 63, 65, 83, 93, 99, 113, 123, 147, 149, 173, 185, 203, 209, 213, 219, 227, 239, 249, 255, 263, 267, 285, 287, 303, 309, 317, 327, 329, 333, 363, 365, 399, 413, 419, 423, 435, 447, 459, 465, 467, 473, 489, 497, 509, 515, 519
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
|
|
|
MAPLE
|
filter:= n -> isprime(n*(10^(1+ilog10(n+4))+1)+4):
select(filter, [seq(i, i=1..1000, 2)]); # Robert Israel, Nov 14 2019
|
|
|
MATHEMATICA
|
prkk4Q[k_]:=With[{c=k+4}, PrimeQ[k*10^IntegerLength[c]+c]]; Select[ Range[ 600], prkk4Q] (* Harvey P. Dale, Aug 31 2021 *)
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn,base
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
