A250049 - OEIS

%I #7 Feb 06 2015 05:52:46

%S 2,3,4,5,12,14,16,18,21,24,26,28,30,35,72,74,75,76,84,86,88,96,98,100,

%T 108,110,111,112,126,129,144,146,147,148,156,158,160,168,170,172,180,

%U 182,183,184,185,210,215,432,434,435,436,444,446,448,450,453,455

%N Numbers n such that m = floor(n/6) is not coprime to n and, if nonzero, m is also a term of the sequence.

%C See the comments in A250041 which all apply, except for the setting of the base, b=6. In particular, they define the property RTNC(b).

%H Stanislav Sykora, <a href="/A250049/b250049.txt">Table of n, a(n) for n = 1..10000</a>

%H Stanislav Sykora, <a href="https://oeis.org/wiki/File:GeneticThreads.txt">PARI/GP scripts for genetic threads</a>, with code and comments.

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

%o (PARI) \\ See A250041 for b=6

%o (PARI) is_rtnc(n, b=6) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b;); return (0); } \\ _Michel Marcus_, Jan 31 2015

%Y Cf. A250041 (b=10), A250046.

%Y Other lists of right-truncatable numbers with the property RTNC(b):

%Y A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250051 (b=5).

%K nonn,base

%O 1,1

%A _Stanislav Sykora_, Jan 31 2015