OFFSET
1,1
COMMENTS
The only prime term is 3 because all primes map to themselves.
EXAMPLE
(15 + 3) / 2 = 9, (9 + 3) / 2 = 6, (6 + 2) / 2 = 4, and (4 + 2) / 2 = 3, thus 15 is in the sequence.
(21 + 3) / 2 = 12, (12 + 2) / 2 = 7, and (7 + 7) / 2 = 7, so 21 never reaches 3 and therefore is not in the sequence.
CROSSREFS
KEYWORD
nonn
AUTHOR
Grant Garcia, Jan 06 2011
STATUS
approved