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A248502 Numbers m that are not coprime to floor(m/16).

%I A248502 #28 Dec 01 2024 04:09:08
%S A248502 2,3,4,5,6,7,8,9,10,11,12,13,14,15,32,34,36,38,40,42,44,46,48,51,54,
%T A248502 57,60,63,64,66,68,70,72,74,76,78,80,85,90,95,96,98,99,100,102,104,
%U A248502 105,106,108,110,111,112,119,126,128,130,132,134,136,138,140,142
%N A248502 Numbers m that are not coprime to floor(m/16).
%C A248502 Definition of 'being coprime' and special-case conventions are as in Wikipedia. In particular, when m < 16 then floor(m/16) = 0, and zero is coprime only to 1. The complementary sequence is A248501.
%C A248502 The asymptotic density of this sequence is 1 - A250031(16)/A250033(16) = 199663/480480 = 0.415549... . - _Amiram Eldar_, Nov 30 2024
%H A248502 Stanislav Sykora, <a href="/A248502/b248502.txt">Table of n, a(n) for n = 1..20000</a>
%H A248502 Wikipedia, <a href="http://en.wikipedia.org/wiki/Coprime_integers">Coprime integers</a>.
%F A248502 gcd(a(n),floor(a(n)/16)) > 1.
%e A248502 2 is a term because gcd(2,0) = 2 > 1.
%e A248502 21 is not a term because floor(21/16) = 1 and 1 is coprime to any number.
%e A248502 200 is a term because floor(200/16) = 12 and gcd(200,12) = 4 > 1.
%t A248502 Select[Range[150], !CoprimeQ[#, Floor[#/16]] &] (* _Amiram Eldar_, Nov 30 2024 *)
%o A248502 (PARI) a=vector(20000);
%o A248502 i=n=0; while(i++, if(gcd(i, i\16)!=1, a[n++]=i; if(n==#a, break))); a
%Y A248502 Cf. A248499, A248500, A248501, A250031, A250033.
%K A248502 nonn,base,easy
%O A248502 1,1
%A A248502 _Stanislav Sykora_, Oct 07 2014