|
|
A110337
|
|
a(n) = 2n+1 if 2n+1 is prime else a(n) = least prime of the form (2n+1)(2n+3)...(2n+2k-1) + 2.
|
|
0
|
|
|
3, 5, 7, 101, 11, 13, 257, 17, 19, 9454727, 23, 677, 801011, 29, 31, 42737, 1297, 37, 1601, 41, 43, 5285387, 47, 410006013351009077, 148667, 53, 3137, 56284059197, 59, 61, 1529270318745462748663049625086428127, 4357, 67, 26822027, 71, 73
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
EXAMPLE
|
a(4) = 9*11+2= 101, as 9 is composite.
|
|
PROG
|
(PARI) a(n) = {pr = 2*n+1; if (isprime(pr), return (pr)); pa = pr; ok = 0; while (! ok, pa += 2; pr *= pa; ok = isprime(pr + 2); ); pr + 2; } \\ Michel Marcus, Sep 16 2013
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
More terms from Victoria Sapko (vsapko(AT)frc.mass.edu), Sep 28 2007
|
|
STATUS
|
approved
|
|
|
|