A250038 - OEIS

%I #25 Jan 21 2015 13:04:25

%S 1,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,257,259,261,263,

%T 265,267,269,271,273,274,275,276,277,278,279,280,281,282,283,284,285,

%U 286,287,289,293,295,299,301,305,306,307,308,309,310,311,312,313,314

%N Numbers n such that m = floor(n/16) is coprime to n and, if nonzero, m is also a term of the sequence.

%C See the comments in A250040 which all apply, except for the setting of the base, b=16. In particular, they define the property RTC(b).

%C This particular list is an infinite subset of A248501.

%H Stanislav Sykora, <a href="/A250038/b250038.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 the link.

%o (PARI) is_rtc(n, b=16) =  {while (((m=gcd(n\b, n)) == 1), if (m == 0, return (1)); if ((n=n\b) == 0, return (1));); return (0);} \\ _Michel Marcus_, Jan 18 2015

%Y Cf. A248501, A250039, A250040.

%Y Other lists of right-truncatable numbers with the property RTC(b): A250036 (b=4), A250040 (b=10), A250042 (b=9), A250044 (b=8), A250046 (b=7), A250048 (b=6), A250050 (b=5).

%K nonn,base

%O 1,2

%A _Stanislav Sykora_, Dec 07 2014