A168008 First differences of A168007.
1, 2, -1, 3, -1, 5, -1, 3, -1, 11, -1, 3, -1, 23, -1, 3, -1, 47, -1, 3, -1, 5, -1, 3, -1, 101, -1, 3, -1, 7, -1, 11, -1, 3, -1, 13, -1, 233, -1, 3, -1, 467, -1, 3, -1, 5, -1, 3, -1, 941, -1, 3, -1, 7, -1, 1889, -1, 3, -1, 3779, -1, 3, -1, 7559, -1, 3, -1, 13, -1
Offset: 1
Keywords
Programs
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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 A168008_list = list(islice(A168008_gen(),20)) # Chai Wah Wu, Mar 14 2023
Extensions
More terms from Jinyuan Wang, Mar 14 2020