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A271504
With a(1) = 1, a(n) is the LCM of all 0 < m < n for which a(m) divides n.
3
1, 1, 2, 6, 2, 60, 2, 210, 2, 630, 2, 13860, 2, 90090, 2, 90090, 2, 3063060, 2, 29099070, 2, 29099070, 2, 1338557220, 2, 3346393050, 2, 10039179150, 2, 582272390700, 2, 9025222055850, 2, 9025222055850, 2, 18050444111700, 2, 333933216066450, 2, 333933216066450
OFFSET
1,3
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..2309 (n = 1..100 from Peter Kagey)
FORMULA
a(2n + 1) = 2 for all n > 1.
a(n) is even for all n > 2.
MATHEMATICA
a = {1}; Do[AppendTo[a, LCM @@ Select[Range[n - 1], Divisible[n, a[[#]]] &]], {n, 2, 40}]; a (* Michael De Vlieger, Apr 08 2016 *)
PROG
(Python 3.9+)
from math import lcm
from itertools import count, islice
from sympy import divisors
def A271504_gen(): # generator of terms
A271504_dict = {1:1}
yield 1
for n in count(2):
yield (s:=lcm(*(A271504_dict.get(d, 1) for d in divisors(n, generator=True))))
A271504_dict[s] = lcm(A271504_dict.get(s, 1), n)
A271504_list = list(islice(A271504_gen(), 40)) # Chai Wah Wu, Nov 17 2022
CROSSREFS
Sequence in context: A122018 A363395 A005729 * A086660 A271503 A102068
KEYWORD
nonn
AUTHOR
Peter Kagey, Apr 08 2016
STATUS
approved