|
|
A172367
|
|
Numbers k > 0 such that k+4 is a prime.
|
|
19
|
|
|
1, 3, 7, 9, 13, 15, 19, 25, 27, 33, 37, 39, 43, 49, 55, 57, 63, 67, 69, 75, 79, 85, 93, 97, 99, 103, 105, 109, 123, 127, 133, 135, 145, 147, 153, 159, 163, 169, 175, 177, 187, 189, 193, 195, 207, 219, 223, 225, 229, 235, 237, 247, 253, 259, 265, 267, 273, 277, 279
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
The subsequence of primes A023200 consists of the smallest primes p of cousin prime pairs (p, p+4), while the subsequence of nonprimes is A164384. - Bernard Schott, Oct 19 2021
|
|
LINKS
|
|
|
FORMULA
|
a(n) = prime(n+2) - 4.
|
|
EXAMPLE
|
a(1) = 5 - 4 = 1, a(2) = 7 - 4 = 3.
|
|
MATHEMATICA
|
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|