OFFSET
1,3
COMMENTS
If p and q are two consecutive odd primes, then p + q is the product of at least three primes (not necessarily distinct) because p + q = 2*(p + q)/2 => (p + q)/2 is a composite integer between two consecutive primes p and q that is the product of at least two prime numbers. Thus 2*(p + q)/2 has at least three prime factors => a(1) = 1 because prime(1) is even => prime(1) + prime(2) = 5 is prime and a(2) = 0, probably the only 0 of the sequence.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..45
EXAMPLE
a(5) = 16 because prime(16) + prime(17) = 53 + 59 = 112 = 7*2^4 with 5 prime divisors.
MATHEMATICA
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Dec 05 2014
EXTENSIONS
a(28)-a(33) from Daniel Suteu, Nov 18 2018
a(34)-a(35) from Giovanni Resta, Nov 19 2018
STATUS
approved