|
|
A139457
|
|
a(n)= smallest m such that primorial(n)/2 + 2^m is prime.
|
|
24
|
|
|
0, 1, 1, 1, 3, 1, 2, 4, 3, 1, 1, 1, 4, 10, 1, 11, 1, 2, 11, 14, 2, 8, 7, 3, 4, 4, 26, 21, 1, 4, 15, 10, 8, 4, 16, 29, 10, 3, 51, 17, 5, 12, 12, 48, 13, 45, 12, 1, 20, 17, 65, 12, 8, 95, 5, 12, 11, 8, 110, 38, 28, 8, 1, 23, 13, 5, 7, 11, 21, 2, 20, 32, 9, 66, 4, 2, 1, 20, 34, 97, 28, 80
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,5
|
|
LINKS
|
|
|
MATHEMATICA
|
k = 1/2; a = {}; Do[k = k*Prime[n]; m = 0; While[ ! PrimeQ[k + 2^m], m++ ]; Print[m]; AppendTo[a, m], {n, 100}]; a
|
|
PROG
|
(PARI) a(n)=my(t=prod(i=2, n, prime(i)), m); while(!isprime(t+2^m), m++); m \\ Charles R Greathouse IV, Apr 28 2015
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
a(1)=0 inserted and program corrected by Ray Chandler, Jun 16 2013
|
|
STATUS
|
approved
|
|
|
|