A186985 Number of 9-element subsets of {1, 2, ..., n} having pairwise coprime elements.

8, 8, 8, 8, 89, 90, 164, 168, 238, 244, 1300, 1301, 4941, 5734, 6132, 6379, 7000, 7089, 22019, 22975, 24637, 25150, 67393, 67678, 160771, 167602, 174367, 182152, 395833, 401344, 563893, 577192, 621709, 646954, 1280587, 1297318, 1442533, 1478536

Offset

19,1

Links

Alois P. Heinz, Table of n, a(n) for n = 19..200

Example

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

Crossrefs

Column 9 of triangle A186974. Partial sums of A186980.

Sequence in context: A166082 A145446 A248762 * A203127 A023415 A294659

Adjacent sequences: A186982 A186983 A186984 * A186986 A186987 A186988

Keyword

nonn

Author

Alois P. Heinz, Mar 02 2011

Status

approved