OFFSET
1,1
COMMENTS
Primes p such that p+1 has at most one odd prime divisor.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
N:= 1000: # to get all terms <= N
Primes:= select(isprime, [$3..(N+1)/2]):
sort(convert(select(isprime, {2, seq(seq(seq(2^r*p^s-1, r = 1 .. ilog2((N+1)/p^s)), s=0..floor(log[p]((N+1)/2))), p=Primes)}), list)); # Robert Israel, Jun 13 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Ray Chandler, Aug 02 2003
STATUS
approved