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 A187265 #9 Aug 15 2014 06:46:28
%S A187265 1,3,7,11,23,27,53,68,97,109,193,208,345,382,437,506,785,827,1224,
%T A187265 1310,1472,1590,2253,2346,2892,3100,3568,3784,5070,5163,6756,7277,
%U A187265 7928,8387,9301,9560,12142,12790,13815,14297,17795,18083,22189
%N A187265 Number of nonempty subsets of {1, 2, ..., n} with <= 4 pairwise coprime elements.
%H A187265 Alois P. Heinz, <a href="/A187265/b187265.txt">Table of n, a(n) for n = 1..1000</a>
%F A187265 a(n) = A187262(n,4).
%e A187265 a(5) = 23 because there are 23 nonempty subsets of {1,2,3,4,5} with <=4 pairwise coprime elements: {1}, {2}, {3}, {4}, {5}, {1,2}, {1,3}, {1,4}, {1,5}, {2,3}, {2,5}, {3,4}, {3,5}, {4,5}, {1,2,3}, {1,2,5}, {1,3,4}, {1,3,5}, {1,4,5}, {2,3,5}, {3,4,5}, {1,2,3,5}, {1,3,4,5}.
%Y A187265 Column 4 of triangle A187262. First differences are A186988.
%K A187265 nonn
%O A187265 1,2
%A A187265 _Alois P. Heinz_, Mar 07 2011