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 A187265 Number of nonempty subsets of {1, 2, ..., n} with <= 4 pairwise coprime elements. 2
 1, 3, 7, 11, 23, 27, 53, 68, 97, 109, 193, 208, 345, 382, 437, 506, 785, 827, 1224, 1310, 1472, 1590, 2253, 2346, 2892, 3100, 3568, 3784, 5070, 5163, 6756, 7277, 7928, 8387, 9301, 9560, 12142, 12790, 13815, 14297, 17795, 18083, 22189 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Alois P. Heinz, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A187262(n,4). EXAMPLE a(5) = 23 because there are 23 nonempty subsets of {1,2,3,4,5} with <=4 pairwise coprime elements: {1}, {2}, {3}, {4}, {5}, {1,2}, {1,3}, {1,4}, {1,5}, {2,3}, {2,5}, {3,4}, {3,5}, {4,5}, {1,2,3}, {1,2,5}, {1,3,4}, {1,3,5}, {1,4,5}, {2,3,5}, {3,4,5}, {1,2,3,5}, {1,3,4,5}. CROSSREFS Column 4 of triangle A187262. First differences are A186988. Sequence in context: A244572 A137516 A247380 * A187266 A187267 A187268 Adjacent sequences: A187262 A187263 A187264 * A187266 A187267 A187268 KEYWORD nonn AUTHOR Alois P. Heinz, Mar 07 2011 STATUS approved

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Last modified September 10 06:17 EDT 2024. Contains 375773 sequences. (Running on oeis4.)