23,1

Alois P. Heinz, Table of n, a(n) for n = 23..200

a(24) = 8 because there are 8 10-element subsets of {1, 2, ..., 24} having pairwise coprime elements: {1,2,3,5,7,11,13,17,19,23}, {1,2,5,7,9,11,13,17,19,23}, {1,3,4,5,7,11,13,17,19,23}, {1,3,5,7,8,11,13,17,19,23}, {1,3,5,7,11,13,16,17,19,23}, {1,4,5,7,9,11,13,17,19,23}, {1,5,7,8,9,11,13,17,19,23}, {1,5,7,9,11,13,16,17,19,23}.

Column 10 of triangle A186974. Partial sums of A186981.

Sequence in context: A205709 A028997 A168397 * A112439 A309461 A245420

Adjacent sequences: A186983 A186984 A186985 * A186987 A186988 A186989

nonn

Alois P. Heinz, Mar 02 2011

approved