|
| |
|
|
A098016
|
|
Indices x such that (1/4)(prime(x+1) + prime(x)) is prime.
|
|
0
| |
|
|
2, 3, 9, 11, 23, 32, 54, 58, 67, 76, 86, 103, 164, 188, 200, 202, 208, 210, 243, 311, 351, 354, 374, 414, 420, 427, 441, 468, 515, 539, 559, 588, 621, 639, 650, 652, 662, 670, 693, 708, 748, 752, 769, 811, 816, 823, 842, 883, 889, 939, 943, 963, 970, 1006, 1009
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
COMMENTS
| Conjecture: 1/2(prime(x+1) + prime(x)) is not prime for all x.
|
|
|
EXAMPLE
| Prime(2+1) + prime(2) = 5+3 = 8. 1/4(8) = 2. 2 is the first entry.
|
|
|
MATHEMATICA
| Transpose[Select[Table[{i, Prime[i], Prime[i+1]}, {i, 1200}], PrimeQ[Total[Rest[#]]/4]&]][[1]](* From Harvey P. Dale, Mar 24 2011 *)
|
|
|
PROG
| (PARI) f(n) = for(x=1, n, y=prime(x+1)+prime(x); if(y%4==0 && isprime(y\4), print1(x", ")))
|
|
|
CROSSREFS
| Sequence in context: A177950 A049618 A057292 * A089645 A088086 A088084
Adjacent sequences: A098013 A098014 A098015 * A098017 A098018 A098019
|
|
|
KEYWORD
| easy,nonn
|
|
|
AUTHOR
| Cino Hilliard (hillcino368(AT)gmail.com), Sep 09 2004
|
| |
|
|
