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 A186987 #13 Oct 04 2018 18:48:18
%S A186987 1,2,4,4,10,4,18,11,19,10,42,11,58,21,30,33,96,22,120,36,62,48,172,37,
%T A186987 147,69,128,70,270,37,308,123,158,117,208,75,432,147,218,119,530,78,
%U A186987 584,186,228,212,696,133,594,191,380,256,882,166,547
%N A186987 Number of subsets of {1, 2, ..., n} containing n and having <=3 pairwise coprime elements.
%H A186987 Alois P. Heinz, <a href="/A186987/b186987.txt">Table of n, a(n) for n = 1..10000</a>
%e A186987 a(6) = 4 because there are 4 subsets of {1,2,3,4,5,6} containing 6 and having <=3 pairwise coprime elements: {6}, {1,6}, {5,6}, {1,5,6}.
%Y A186987 Column 3 of triangle A186975. Sum of A039649 and A185953 for n>1.
%K A186987 nonn,look
%O A186987 1,2
%A A186987 _Alois P. Heinz_, Mar 03 2011