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A119251
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Positive integers each with exactly 1 unitary prime divisor (i.e., n is included if and only if A056169(n) = 1).
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1
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2, 3, 5, 7, 11, 12, 13, 17, 18, 19, 20, 23, 24, 28, 29, 31, 37, 40, 41, 43, 44, 45, 47, 48, 50, 52, 53, 54, 56, 59, 61, 63, 67, 68, 71, 73, 75, 76, 79, 80, 83, 88, 89, 92, 96, 97, 98, 99, 101, 103, 104, 107, 109, 112, 113, 116, 117, 124, 127, 131, 135, 136, 137, 139, 147
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OFFSET
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1,1
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COMMENTS
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Also, numbers expressible as the product of a prime and a powerful number not divisible by that prime. - Franklin T. Adams-Watters, Jul 25 2006
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LINKS
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EXAMPLE
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28 has the prime factorization of 2^2 * 7^1. 28 is therefore included in this sequence because there is exactly one prime raised to an exponent of 1 in 28's prime factorization.
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MATHEMATICA
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Select[Range@147, Count[FactorInteger@#, 1, 2] == 1 &] (* Robert G. Wilson v, Jul 25 2006 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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