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%I #21 Apr 03 2024 14:43:42
%S 2,3,4,5,6,7,8,9,10,12,14,15,16,18,20,21,22,24,25,26,27,28,30,32,33,
%T 34,35,36,38,39,40,42,44,45,46,48,49,50,51,52,54,55,56,57,58,60,62,63,
%U 64,65,66,68,69,70,72,74,75,76,77,78,80,81,82,84,85,86,87,88,90,91,92,93
%N Numbers having divisors 2 or 3 or 5 or 7.
%C A020639(a(n)) <= 7; A210679(a(n)) > 0. - _Reinhard Zumkeller_, Apr 02 2012
%H Reinhard Zumkeller, <a href="/A080672/b080672.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Rec#order_162">Index entries for linear recurrences with constant coefficients</a>, order 162.
%F From _Charles R Greathouse IV_, Sep 14 2015: (Start)
%F a(n) = 35n/27 + O(1).
%F For n > 162, a(n) = a(n-162) + 210. [Corrected by _Peter Munn_, Apr 22 2021]
%F (End)
%F For n < 162, a(n) = 210 - a(162-n). - _Peter Munn_, Apr 22 2021
%t Select[Range[100],Length[Intersection[Divisors[#],{2,3,5,7}]]>0&] (* _Harvey P. Dale_, Apr 03 2024 *)
%o (PARI) div2357(n)= for(x=1,n, if(gcd(x,210)<>1,print1(x" ")) )
%o (PARI) is(n)=gcd(n,210)>1 \\ _Charles R Greathouse IV_, Sep 14 2015
%o (Haskell)
%o a080672 n = a080672_list !! (n-1)
%o a080672_list = filter ((<= 7) . a020639) [2..]
%o -- _Reinhard Zumkeller_, Apr 02 2012
%Y Cf. A020639, A008364 (complement).
%Y Subsequences: A002473, A343597.
%K easy,nonn
%O 1,1
%A _Cino Hilliard_, Mar 02 2003
%E Offset fixed by _Reinhard Zumkeller_, Apr 02 2012
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