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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 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.)