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 A250051 #7 Feb 06 2015 05:52:27
%S A250051 2,3,4,10,12,14,15,18,20,22,24,50,52,54,60,62,63,64,70,72,74,75,78,90,
%T A250051 92,93,94,100,102,104,110,112,114,120,122,123,124,250,252,254,260,262,
%U A250051 264,270,272,273,274,300,302,303,304,310,312,314,315,318
%N A250051 Numbers n such that m = floor(n/5) is not coprime to n and, if nonzero, m is also a term of the sequence.
%C A250051 See the comments in A250041 which all apply, except for the setting of the base, b=5. In particular, they define the property RTNC(b).
%H A250051 Stanislav Sykora, <a href="/A250051/b250051.txt">Table of n, a(n) for n = 1..10000</a>
%H A250051 Stanislav Sykora, <a href="https://oeis.org/wiki/File:GeneticThreads.txt">PARI/GP scripts for genetic threads</a>, with code and comments.
%H A250051 Wikipedia, <a href="http://en.wikipedia.org/wiki/Coprime_integers">Coprime integers</a>
%o A250051 (PARI) \\ See A250041 for b=5
%o A250051 (PARI) is_rtnc(n, b=5) = {while (((m=gcd(n\b, n)) != 1), if (m == 0, return (1)); n = n\b;); return (0);} \\ _Michel Marcus_, Jan 31 2015
%Y A250051 Cf. A250041 (b=10), A250046.
%Y A250051 Other lists of right-truncatable numbers with the property RTNC(b):
%Y A250051 A005823 (b=3), A250037 (b=4), A250039 (b=16), A250043 (b=9), A250045 (b=8), A250047 (b=7), A250049 (b=6).
%K A250051 nonn,base
%O A250051 1,1
%A A250051 _Stanislav Sykora_, Jan 31 2015