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A166063 23-rough numbers: positive integers that have no prime factors less than 23. 11
1, 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, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Or, positive integers relatively prime to 9699690 = 2*3*5*7*11*13*17*19.

First composite term is 529 = 23^2.

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1200

Eric Weisstein's World of Mathematics, Rough Number

Index entries for sequences related to smooth numbers

FORMULA

a(n) = k*n + O(1) where k = 323323/55296 = 5.8471.... In particular, k*n - 51 < a(n) < k*n + 45. - Charles R Greathouse IV, Sep 21 2018

EXAMPLE

667 = 23 * 29 is in the sequence since the two prime factors, 23 and 29, are not less than 23.

MATHEMATICA

Select[Range[500], FactorInteger[#][[1, 1]]>22&] (* Harvey P. Dale, Nov 22 2010 *)

PROG

(PARI) isA166063(n) = gcd(n, 9699690)==1 \\ Michael B. Porter, Oct 10 2009

CROSSREFS

k-rough numbers: A000027, A005408, A007310, A007775, A008364, A008365, A008366, A166061, A166063.

Sequence in context: A255220 A060703 A061753 * A231073 A049483 A112681

Adjacent sequences:  A166060 A166061 A166062 * A166064 A166065 A166066

KEYWORD

easy,nonn

AUTHOR

Michael B. Porter, Oct 05 2009

EXTENSIONS

Additional terms provided provided by Harvey P. Dale, Nov 22 2010

STATUS

approved

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Last modified September 24 21:35 EDT 2020. Contains 337322 sequences. (Running on oeis4.)