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A186983
Number of 7-element subsets of {1, 2, ..., n} having pairwise coprime elements.
3
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
OFFSET
13,1
LINKS
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
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Mar 02 2011
STATUS
approved