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 A078861 #4 Oct 15 2013 22:31:46
%S A078861 11,13,17,23,31,37,41,47,53,61,67,73,83,97,101,103,107,121,131,137,
%T A078861 143,151,157,163,167,173,181,187,191,193
%N A078861 Least positive residues [mod 210] representing those residue classes which can be smaller prime of a difference 6 taken from A031924.
%F A078861 Intersection[RRS(210), 6+RRS{210)]-6. RRS[210]=reduced residue system of 210=first 48=phi[210] terms of A008364; 210k+r generates complete A031924 with suitable k and r taken from these 30 numbers.
%t A078861 t=Flatten[Position[Table[GCD[w, 210], {w, 1, 210}], 1]] t2=Intersection[t, t+6]-6
%Y A078861 Cf. A031924, A008364, A078859, A078860.
%K A078861 fini,full,nonn
%O A078861 1,1
%A A078861 _Labos Elemer_, Dec 13 2002