A186982 Number of 6-element subsets of {1, 2, ..., n} having pairwise coprime elements.

6, 6, 39, 41, 44, 56, 213, 219, 619, 655, 731, 777, 1853, 1909, 2775, 2961, 3707, 3923, 7803, 7859, 14308, 15876, 17437, 18459, 20865, 21313, 36080, 38103, 41568, 42828, 68688, 69360, 106470, 111456, 117033, 122883, 181854, 185066, 230208, 236610

Offset: 11

Author

Alois P. Heinz, Mar 02 2011

Keywords

• nonn

Examples

			a(12) = 6 because there are 6 6-element subsets of {1, 2, ..., 12} having pairwise coprime elements: {1,2,3,5,7,11}, {1,5,7,8,9,11}, {1,4,5,7,9,11}, {1,3,5,7,8,11}, {1,3,4,5,7,11}, {1,2,5,7,9,11}.
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 11..200

Crossrefs

Column 6 of triangle A186974. Partial sums of A186977.