OFFSET
1,2
PROG
(Python)
from itertools import count, islice
from sympy import primefactors
def A168008_gen(): # generator of terms
a = 1
for n in count(2):
yield (b:=min(primefactors(a), default=1) if a&1 or a==2 else -1)
a += b
CROSSREFS
KEYWORD
sign
AUTHOR
Omar E. Pol, Nov 19 2009
EXTENSIONS
More terms from Jinyuan Wang, Mar 14 2020
STATUS
approved