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 A250050 #7 Feb 06 2015 05:53:13
%S A250050 1,5,6,7,8,9,26,27,28,29,31,36,37,38,39,41,43,46,47,49,131,133,136,
%T A250050 137,139,141,143,146,147,148,149,156,157,158,159,181,186,187,188,189,
%U A250050 191,193,196,197,199,206,207,208,209,216,217,218,219,231,233,236,237
%N A250050 Numbers n such that m = floor(n/5) is coprime to n and, if nonzero, m is also a term of the sequence.
%C A250050 See the comments in A250040 which all apply, except for the setting of the base, b=5. In particular, they define the property RTC(b).
%H A250050 Stanislav Sykora, <a href="/A250050/b250050.txt">Table of n, a(n) for n = 1..10000</a>
%H A250050 Stanislav Sykora, <a href="https://oeis.org/wiki/File:GeneticThreads.txt">PARI/GP scripts for genetic threads</a>, with code and comments.
%H A250050 Wikipedia, <a href="http://en.wikipedia.org/wiki/Coprime_integers">Coprime integers</a>
%o A250050 (PARI) \\ See A250040 for b=5
%o A250050 (PARI) is_rtc(n, b=5) = {while (((m=gcd(n\b, n)) == 1), if (m == 0, return (1)); if ((n=n\b) == 0, return (1));); return (0);} \\ _Michel Marcus_, Jan 31 2015
%Y A250050 Cf. A250040 (b=10), A250047.
%Y A250050 Other lists of right-truncatable numbers with the property RTC(b): A250036 (b=4), A250038 (b=16), A250042 (b=9), A250044 (b=8), A250046 (b=7), A250048 (b=6).
%K A250050 nonn,base
%O A250050 1,2
%A A250050 _Stanislav Sykora_, Jan 31 2015