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A356438
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Numbers k such that A309892(k) = k/gpf(k), where gpf = A006530.
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3
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1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 17, 19, 20, 21, 22, 23, 25, 26, 28, 29, 30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 44, 46, 47, 49, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 65, 66, 67, 68, 69, 70, 71, 73, 74, 76, 77, 78, 79, 82, 83, 85
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OFFSET
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1,2
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COMMENTS
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Note that A309892(k) <= k/gpf(k); these sequence lists k such that the equality holds.
For k >= 2, k is a term if and only if k/gpf(k) < nextprime(gpf(k)), where nextprime = A151800.
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LINKS
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EXAMPLE
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15 is a term since the number of steps needed to reach 0 of the iteration x -> x - gpf(x) starting at 15 is 3: 15 -> 10 -> 5 -> 0, and 3 = 15/gpf(15).
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PROG
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(PARI) isA356438(n) = if(n>1, my(p=vecmax(factor(n)[, 1])); n/p<nextprime(p+1), 1)
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CROSSREFS
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Other than 1, indices of 1 in A356428.
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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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