OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
103 = (51+1)*2^1-1 = (25+1)*2^2-1 = (12+1)*2^3-1, the numbers 51, 25 and 12 are not primes, so 103 is in the sequence.
71 = (35+1)*2^1-1 = (17+1)*2^2-1 = (8+1)*2^3-1, the number 17 is prime, so 71 is not in the sequence.
MAPLE
filter := proc(n) local k;
if not isprime(n) then return false fi;
for k from 1 to padic:-ordp(n+1, 2) do
if isprime((n+1)/2^k-1) then return false
fi
od:
true
end proc:
select(filter, [2, seq(i, i=3..1000, 2)]); # Robert Israel, Jun 29 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Gionata Neri, Jun 29 2016
STATUS
approved