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

11,1

Links

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

Example

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}.

Crossrefs

Column 6 of triangle A186974. Partial sums of A186977.

Sequence in context: A203057 A165424 A244957 * A196075 A156099 A278435

Adjacent sequences: A186979 A186980 A186981 * A186983 A186984 A186985

Keyword

nonn

Author

Alois P. Heinz, Mar 02 2011

Status

approved