OFFSET
1,1
COMMENTS
Also, primes sandwiched by 3-almost primes. Primes p such that p-+1 are 3-almost primes (A014612). - Zak Seidov, Jul 06 2015
LINKS
Robert G. Wilson v, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harry J. Smith)
EXAMPLE
MATHEMATICA
Select[Prime[Range[3000]], 3 == PrimeOmega[# - 1] == PrimeOmega[# + 1] &] (* Vincenzo Librandi, Jul 07 2015 *)
PROG
(PARI) n=0; default(primelimit, 2000000); for (m=2, 10^9, p=prime(m); if (bigomega(p + 1) == 3 && bigomega(p - 1) == 3, write("b063644.txt", n++, " ", p); if (n==1000, break)) ) \\ Harry J. Smith, Aug 27 2009
(PARI) list(lim)=my(v=List(), u=v, L=(lim+1)\2, t); forprime(p=2, L\2, forprime(q=2, min(p, L\p), listput(u, p*q))); u=Set(u); for(i=2, #u, if(u[i]-u[i-1]==1 && isprime(t=2*u[i]-1), listput(v, t))); Vec(v) \\ Charles R Greathouse IV, Jan 31 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 21 2001
STATUS
approved