OFFSET
1,1
COMMENTS
LINKS
Max Alekseyev, Table of n, a(n) for n=1..230
EXAMPLE
For p = 31, one half of 31^2 - 3*31 - 2 equals 433, which is prime.
MAPLE
a:=proc(n) local b: b:=ithprime(n): if isprime((b^2-3*b-2)/2)=true then b else fi end: seq(a(n), n=1..300); # Emeric Deutsch, May 25 2007
isA129842 := proc(p) if isprime(p) then isprime((p^2-3*p-2)/2) ; else false ; fi ; end: for n from 1 to 880 do p := ithprime(n) : if isA129842(p) then printf("%d, ", p) ; fi ; od : # R. J. Mathar, Jun 08 2007
MATHEMATICA
Select[Prime[Range[2, 224]], PrimeQ[(#^2 - 3*# - 2)/2] &] (* Stefan Steinerberger, Jun 23 2007 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot, May 22 2007
EXTENSIONS
More terms from Emeric Deutsch and R. J. Mathar, May 25 2007
STATUS
approved