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A166061
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19-rough numbers: positive integers that have no prime factors less than 19
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7
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1, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Or, positive integers relatively prime to 510510 = 2*3*5*7*11*13*17.
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LINKS
| Eric Weisstein's World of Mathematics, Rough Number
Index entries for sequences related to smooth numbers [From Michael Porter (michael_b_porter(AT)yahoo.com), Oct 10 2009]
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EXAMPLE
| 437 = 19 * 23 is in the sequence since the two prime factors, 19 and 23, are not less than 19.
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PROG
| (PARI) isA166061(n) = gcd(n, 510510)==1 [From Michael Porter (michael_b_porter(AT)yahoo.com), Oct 10 2009]
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CROSSREFS
| For k-rough numbers with other values of k, see A000027 A005408 A007310 A007775 A008364 A008365 A008366 A166061 A166063 [From Michael Porter (michael_b_porter(AT)yahoo.com), Oct 10 2009]
Sequence in context: A070299 A159021 A100460 * A073319 A120640 A151768
Adjacent sequences: A166058 A166059 A166060 * A166062 A166063 A166064
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KEYWORD
| easy,nonn
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AUTHOR
| Michael Porter (michael_b_porter(AT)yahoo.com), Oct 05 2009
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