A186983 - OEIS

A186983

Number of 7-element subsets of {1, 2, ..., n} having pairwise coprime elements.

6, 6, 6, 8, 64, 65, 284, 297, 324, 339, 1116, 1144, 1784, 1886, 2449, 2576, 6499, 6527, 14386, 16178, 17683, 18649, 21003, 21395, 42708, 44997, 48966, 50310, 93138, 93852, 163212, 170778, 178896, 187722, 310605, 315687, 408771, 419661, 453255

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OFFSET

13,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 13..200

EXAMPLE

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

CROSSREFS

Column 7 of triangle A186974. Partial sums of A186978.

Sequence in context: A361871 A179415 A179409 * A046264 A291989 A035019

Adjacent sequences: A186980 A186981 A186982 * A186984 A186985 A186986

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Mar 02 2011

STATUS

approved