|
|
A171135
|
|
Smallest prime p such that p + 2n is prime or semiprime.
|
|
3
|
|
|
2, 2, 3, 2, 3, 2, 3, 3, 3, 2, 3, 2, 3, 3, 3, 2, 3, 2, 3, 3, 5, 2, 3, 3, 3, 3, 3, 2, 3, 2, 3, 3, 3, 3, 3, 2, 3, 3, 5, 2, 3, 2, 3, 3, 3, 2, 3, 5, 3, 3, 5, 2, 3, 3, 3, 3, 5, 2, 3, 2, 5, 3, 3, 3, 3, 2, 3, 3, 3, 2, 3, 2, 3, 3, 5, 3, 3, 2, 3, 3, 5, 2, 3, 5, 3, 5, 3, 2, 3, 3, 3, 3, 5, 3, 3, 2, 3, 3, 3, 2, 3, 2, 3, 3, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
For any even integer h, there exist infinitely many primes p such that p+h is either a prime or a semiprime;
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
spp[n_]:=Module[{p=2}, While[PrimeOmega[p+2n]>2, p=NextPrime[p]]; p]; Array[ spp, 120] (* Harvey P. Dale, Sep 25 2018 *)
|
|
PROG
|
(Haskell)
a171135 n = head [p | p <- a000040_list, let x = p + 2 * n,
a064911 x == 1 || a010051' x == 1]
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|