A187491 Number of 4-element nondividing subsets of {1, 2, ..., n}.

1, 2, 3, 6, 10, 21, 32, 49, 65, 101, 150, 224, 305, 413, 525, 707, 908, 1174, 1479, 1871, 2269, 2826, 3396, 4138, 4967, 5991, 6917, 8244, 9673, 11328, 12958, 15091, 17112, 19771, 22468, 25485, 28870, 32861, 36298, 40969, 45615, 51015

Offset

10,2

Comments

A set is called nondividing if no element divides the sum of any nonempty subset of the other elements.

Links

Table of n, a(n) for n=10..51.

Eric Weisstein's World of Mathematics, Nondividing Set

Example

a(10) = 1 because there is one 4-element nondividing subset of {1,2,...,10}: {6,7,9,10}.

Crossrefs

Column 4 of triangle A187489. Cf. A068063.

Sequence in context: A047111 A106741 A068991 * A178852 A215067 A008928

Adjacent sequences: A187488 A187489 A187490 * A187492 A187493 A187494

Keyword

nonn

Author

Alois P. Heinz, Mar 10 2011

Status

approved