A187492 Number of 5-element nondividing subsets of {1, 2, ..., n}.

2, 4, 6, 11, 15, 24, 50, 83, 127, 209, 310, 431, 679, 921, 1229, 1624, 2145, 2770, 3752, 4866, 6141, 7753, 9679, 12005, 15027, 18134, 22045, 26368, 31712, 37763, 45569, 53810, 63393, 73560, 86496, 100071, 117234, 134623, 155465, 176876

Offset

21,1

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=21..60.

Eric Weisstein's World of Mathematics, Nondividing Set

Example

a(21) = 2 because there are two 5-element nondividing subsets of {1,2,...,21}: {12,16,18,19,21}, {12,14,18,20,21}.

Crossrefs

Column 5 of triangle A187489. Cf. A068063.

Sequence in context: A238487 A138461 A173397 * A366127 A103580 A094866

Adjacent sequences: A187489 A187490 A187491 * A187493 A187494 A187495

Keyword

nonn

Author

Alois P. Heinz, Mar 10 2011

Status

approved