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A248500 Numbers m that are not coprime to A059995(m): floor(m/10). 6


%S 2,3,4,5,6,7,8,9,20,22,24,26,28,30,33,36,39,40,42,44,46,48,50,55,60,

%T 62,63,64,66,68,69,70,77,80,82,84,86,88,90,93,96,99,100,102,104,105,

%U 106,108,110,120,122,123,124,126,128,129,130,140,142,144,146,147

%N Numbers m that are not coprime to A059995(m): floor(m/10).

%C Definition of 'being coprime' and special-case conventions are as in Wikipedia. In particular, when m<10 then floor(m/10)=0, and zero is coprime only to 1. The complementary sequence is A248499.

%H Stanislav Sykora, <a href="/A248500/b248500.txt">Table of n, a(n) for n = 1..20000</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Coprime_integers">Coprime integers</a>

%F gcd(a(n),floor(a(n)/10)) > 1.

%e 2 is a member because gcd(2,0)=2 > 1.

%e 100 is also a member because gcd(100,10)=10 > 1.

%e 125 is not a member because 125 and 12 are coprime, i.e., gcd(125,12)=1.

%o (PARI) a=vector(20000);

%o i=n=0; while(i++, if(gcd(i, i\10)!=1, a[n++]=i; if(n==#a, break))); a

%Y Cf. A059995, A248499, A248501, A248502.

%K nonn,base,easy

%O 1,1

%A _Stanislav Sykora_, Oct 07 2014

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Last modified June 25 03:40 EDT 2021. Contains 345449 sequences. (Running on oeis4.)