This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A166061 #17 Feb 16 2025 08:33:11
%S A166061 1,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,
%T A166061 109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,
%U A166061 199,211,223,227,229,233,239,241,251,257,263,269,271
%N A166061 19-rough numbers: positive integers that have no prime factors less than 19.
%C A166061 Or, positive integers relatively prime to 510510 = 2*3*5*7*11*13*17.
%H A166061 Harvey P. Dale, <a href="/A166061/b166061.txt">Table of n, a(n) for n = 1..1000</a>
%H A166061 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RoughNumber.html">Rough Number</a>
%H A166061 <a href="/index/Sk#smooth">Index entries for sequences related to smooth numbers</a> [From _Michael B. Porter_, Oct 10 2009]
%F A166061 a(n) = k*n + O(1) where k = 17017/3072 = 5.539388.... In particular, k*n - 31 < a(n) < k*n + 25. - _Charles R Greathouse IV_, Sep 24 2018
%e A166061 437 = 19 * 23 is in the sequence since the two prime factors, 19 and 23, are not less than 19.
%t A166061 Join[{1},Select[Range[300],Min[Transpose[FactorInteger[#]][[1]]]>18&]] (* _Harvey P. Dale_, Feb 18 2015 *)
%o A166061 (PARI) isA166061(n) = gcd(n,510510)==1 \\ _Michael B. Porter_, Oct 10 2009
%Y A166061 k-rough numbers: A000027, A005408, A007310, A007775, A008364, A008365, A008366, A166061, A166063.
%K A166061 easy,nonn
%O A166061 1,2
%A A166061 _Michael B. Porter_, Oct 05 2009