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A180636 Positive integers that are divisible by neither 8k-1 nor 8k+1, for all k > 0.

%I A180636 #12 Nov 04 2024 18:13:33
%S A180636 1,2,3,4,5,6,8,10,11,12,13,16,19,20,22,24,26,29,32,37,38,40,43,44,48,
%T A180636 52,53,58,59,61,64,67,74,76,80,83,86,88,96,101,104,106,107,109,116,
%U A180636 118,122,128,131,134,139,148,149,152,157,160,163,166,172,173,176,179,181,192
%N A180636 Positive integers that are divisible by neither 8k-1 nor 8k+1, for all k > 0.
%H A180636 G. C. Greubel, <a href="/A180636/b180636.txt">Table of n, a(n) for n = 1..5000</a>
%t A180636 fQ[n_] := Union[ MemberQ[{1, 7}, # ] & /@ Union@ Mod[ Rest@ Divisors@ n, 8]] == {False}; fQ[1] = True; Select[ Range@ 200, fQ] (* _Robert G. Wilson v_, Oct 06 2010 *)
%o A180636 (Python) # Works in Python 2 or 3
%o A180636 import itertools
%o A180636 for n in itertools.count(1):
%o A180636     for k in range(1, 2+n//8):
%o A180636         if n%(8*k-1)==0 or n%(8*k+1)==0:
%o A180636             break
%o A180636     else:
%o A180636         print(n)
%Y A180636 Cf. A047424. - _Robert G. Wilson v_, Oct 06 2010
%K A180636 easy,nonn
%O A180636 1,2
%A A180636 _Glenn G. Chappell_, Sep 13 2010
%E A180636 More terms from _Robert G. Wilson v_, Oct 06 2010