OFFSET
1,1
COMMENTS
a(n) = A086005(n)/2.
LINKS
T. D. Noe, Table of n, a(n) for n=1..10000
FORMULA
EXAMPLE
101 is prime and 2*101-1=201=3*67, 2*101+1=203=7*29, therefore 101 is a term.
It is the sixth term and a(6)=101=A086005(6)/2.
MATHEMATICA
Select[Prime[Range[400]], PrimeOmega[2#-1]==PrimeOmega[2#+1]==2&] (* Harvey P. Dale, Jun 23 2016 *)
PROG
(PARI) isok(n) = isprime(n) && (bigomega(2*n+1) == 2) && (bigomega(2*n-1) == 2) \\ Michel Marcus, Aug 01 2013
(Haskell)
a086006 = flip div 2 . a086005 -- Reinhard Zumkeller, Aug 08 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 07 2003
STATUS
approved