|
|
A264526
|
|
Smallest number m such that both 2*n-m and 2*n+m are primes.
|
|
5
|
|
|
1, 1, 3, 3, 1, 3, 3, 1, 3, 9, 5, 3, 9, 1, 9, 3, 5, 9, 3, 1, 3, 15, 5, 3, 9, 7, 3, 15, 1, 9, 3, 5, 15, 3, 1, 15, 3, 5, 9, 15, 5, 3, 9, 7, 9, 15, 7, 9, 3, 1, 3, 3, 1, 3, 15, 13, 15, 9, 7, 9, 15, 13, 21, 21, 5, 3, 27, 1, 9, 15, 5, 33, 9, 1, 15, 3, 7, 9, 3, 5
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
2,3
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
snm[n_]:=Module[{m=1}, While[!PrimeQ[2n-m]||!PrimeQ[2n+m], m=m+2]; m]; Array[ snm, 90, 2] (* Harvey P. Dale, Aug 13 2017, optimized by Ivan N. Ianakiev, Mar 16 2018 *)
|
|
PROG
|
(Haskell)
a264526 = head . a260689_row
(PARI) a(n) = {my(m=1); while(!(isprime(2*n-m) && isprime(2*n+m)), m+=2); m; } \\ Michel Marcus, Mar 18 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|