|
|
A215248
|
|
Numbers n such that n^2 + 1 and (n^2+2)/6 are both primes.
|
|
2
|
|
|
4, 10, 16, 20, 26, 56, 110, 116, 170, 224, 236, 314, 326, 340, 430, 584, 700, 764, 920, 946, 1054, 1106, 1276, 1294, 1406, 1546, 1550, 1654, 1684, 1700, 1756, 1766, 1784, 1816, 2006, 2026, 2116, 2260, 2294, 2314, 2320, 2360, 2576, 2600, 2684, 2746, 2770, 2924
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
n==2 or 4 (mod 6) so that (n^2+2)/6 is an integer. - Robert Israel, May 03 2017
|
|
LINKS
|
|
|
EXAMPLE
|
4 is in the sequence because 4^2+1 = 17 and (4^2+2)/6 = 3 are both primes.
|
|
MAPLE
|
select(t -> isprime(t^2+1) and isprime((t^2+2)/6), [seq(seq(6*j+k, k=[2, 4]), j=0..1000)]); # Robert Israel, May 03 2017
|
|
MATHEMATICA
|
Select[Range[3000], PrimeQ[(#^2+1)]&&PrimeQ[(#^2+2)/6]&]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|