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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
Eric Weisstein's World of Mathematics, Rough Number
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
Sequence in context: A255220 A060703 A061753 * A231073 A049483 A112681
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 March 29 02:16 EDT 2024. Contains 371264 sequences. (Running on oeis4.)