OFFSET
1,1
COMMENTS
Primes p such that p - 1 and p + 1 are 4-almost primes.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
89 - 1 = 2^3*11, 89 + 1 = 2*3^2*5.
MATHEMATICA
Select[Prime[Range[1000]], 4 == PrimeOmega[# - 1] == PrimeOmega[# + 1] &]
PROG
(PARI) forprime(p= 1, 5000, if(4==bigomega(p-1)&&4==bigomega(p+1), print1(p", ")))
(PARI) is(n)=bigomega(n-1)==4 && bigomega(n+1)==4 && isprime(n) \\ Charles R Greathouse IV, Apr 27 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Jan 10 2015
STATUS
approved