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1, 2, 3, 2, 5, 6, 7, 4, 3, 10, 11, 6, 13, 14, 15, 8, 17, 18, 19, 10, 21, 22, 23, 12, 5, 26, 9, 14, 29, 30, 31, 16, 33, 34, 35, 18, 37, 38, 39, 20, 41, 42, 43, 22, 15, 46, 47, 24, 7, 50, 51, 26, 53, 54, 55, 28, 57, 58, 59, 30, 61, 62, 21, 32, 65, 66, 67, 34, 69
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OFFSET
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1,2
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LINKS
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FORMULA
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a(n) <= n.
a(p) = p, for p prime.
Suppose n>1 and p = A020639(n). a(n) = n if p^2 does not divide n and a(n) = n/p otherwise. - Chai Wah Wu, Apr 04 2024
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MATHEMATICA
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Join[{1}, Map[LCM[#[[2]], #[[-2]]] &, Divisors[Range[2, 100]]]]
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PROG
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(PARI) a(n) = if (n==1, 1, my(x=factor(n)[1, 1]); lcm(x, n/x)); \\ Michel Marcus, Apr 02 2024
(Python)
from math import lcm
from sympy import factorint
def a(n): return 1 if n==1 else lcm((p:=min(factorint(n))), n//p)
(Python)
from sympy import factorint
def A371573(n): return n if (p:=min(factorint(n).items(), default=(1, 1)))[1] == 1 else n//p[0] # Chai Wah Wu, Apr 04 2024
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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