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A067026
(Prime(n)# - 4)/2 is prime, where x# is the primorial A034386(x).
24
3, 4, 5, 6, 7, 8, 9, 11, 13, 16, 20, 27, 39, 83, 103, 122, 129, 145, 279, 393, 608, 798, 929, 1164, 1266, 1491, 2043, 3276, 3426, 7119, 15711, 18424
OFFSET
1,1
COMMENTS
n such that A002110(n)/2 - 2 is prime.
a(33) > 25000. - Robert Price, Sep 29 2017
MATHEMATICA
p = 1; Do[p = p*Prime[n]; If[PrimeQ[(p - 4)/2], Print[n]], {n, 1, 400} ]
Flatten[Position[Rest[FoldList[Times, 1, Prime[Range[2100]]]], _?(PrimeQ[(#-4)/2]&)]] (* Harvey P. Dale, Nov 22 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 29 2001
EXTENSIONS
More terms from Robert G. Wilson v, Dec 30 2001
a(21)-a(27) from Ray Chandler, Jun 16 2013
a(28)-a(32) from Robert Price, Sep 29 2017
STATUS
approved