This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A250036 #21 Jan 21 2015 13:04:20
%S A250036 1,4,5,6,7,17,19,21,22,23,25,29,30,31,69,70,71,77,78,79,85,86,89,91,
%T A250036 93,94,95,101,102,103,117,118,119,121,125,126,127,277,278,281,283,285,
%U A250036 286,287,309,310,311,313,317,318,319,341,342,343,345,347,357,358
%N A250036 Numbers n such that m = floor(n/4) is coprime to n and, if nonzero, m is also a term of the sequence.
%C A250036 See the comments in A250040 which all apply, except for the setting of the base, b=4. In particular, they define the property RTC(b).
%H A250036 Stanislav Sykora, <a href="/A250036/b250036.txt">Table of n, a(n) for n = 1..10000</a>
%H A250036 Stanislav Sykora, <a href="https://oeis.org/wiki/File:GeneticThreads.txt">PARI/GP scripts for genetic threads</a>, with code and comments.
%H A250036 Wikipedia, <a href="http://en.wikipedia.org/wiki/Coprime_integers">Coprime integers</a>
%o A250036 (PARI) See the link.
%o A250036 (PARI) is_rtc(n, b=4) = {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 A250036 Cf. A250037, A250040.
%Y A250036 Other lists of right-truncatable numbers with the property RTC(b): A250038 (b=16), A250040 (b=10), A250042 (b=9), A250044 (b=8), A250046 (b=7), A250048 (b=6), A250050 (b=5).
%K A250036 nonn,base
%O A250036 1,2
%A A250036 _Stanislav Sykora_, Dec 07 2014