A186988 - OEIS

%I #9 Mar 30 2012 17:37:34

%S 1,2,4,4,12,4,26,15,29,12,84,15,137,37,55,69,279,42,397,86,162,118,

%T 663,93,546,208,468,216,1286,93,1593,521,651,459,914,259,2582,648,

%U 1025,482,3498,288,4106,961,1163,1116,5316,641,4326,1033

%N Number of subsets of {1, 2, ..., n} containing n and having <=4 pairwise coprime elements.

%H Alois P. Heinz, <a href="/A186988/b186988.txt">Table of n, a(n) for n = 1..1000</a>

%e a(5) = 12 because there are 12 subsets of {1,2,3,4,5} containing 5 and having <=4 pairwise coprime elements: {5}, {1,5}, {2,5}, {3,5}, {4,5}, {1,2,5}, {1,3,5}, {1,4,5}, {2,3,5}, {3,4,5}, {1,2,3,5}, {1,3,4,5}.

%Y Column 4 of triangle A186975. Sum of A186987 and A185348.

%K nonn

%O 1,2

%A _Alois P. Heinz_, Mar 03 2011