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A076563
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a(n) = n - greatest prime divisor of n, for n>1.
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12
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0, 0, 2, 0, 3, 0, 6, 6, 5, 0, 9, 0, 7, 10, 14, 0, 15, 0, 15, 14, 11, 0, 21, 20, 13, 24, 21, 0, 25, 0, 30, 22, 17, 28, 33, 0, 19, 26, 35, 0, 35, 0, 33, 40, 23, 0, 45, 42, 45, 34, 39, 0, 51, 44, 49, 38, 29, 0, 55, 0, 31, 56, 62, 52, 55, 0, 51, 46, 63, 0, 69, 0, 37, 70, 57, 66, 65, 0, 75
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OFFSET
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2,3
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LINKS
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FORMULA
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a(p) = 0 for prime p.
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MATHEMATICA
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PROG
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(PARI) a(n) = n - vecmax(factor(n)[, 1]); \\ Michel Marcus, Aug 07 2022
(Python)
from sympy import factorint
def a(n): return n - max(factorint(n))
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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