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A270970
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Number of subsets of {1,...,n} with sum of elements equal to least common multiple of elements.
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2
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1, 2, 4, 5, 6, 8, 9, 11, 14, 16, 17, 21, 22, 24, 28, 31, 32, 37, 38, 53, 56, 57, 58, 71, 72, 73, 77, 85, 86, 131, 132, 138, 141, 142, 143, 163, 164, 165, 167, 289, 290, 310, 311, 316, 403, 404, 405, 454, 455, 458, 460, 463, 464, 478, 479, 557, 559, 560, 561
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OFFSET
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1,2
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COMMENTS
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Similar to A270875 but also counts singletons, the trivial solutions.
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LINKS
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Hiroaki Yamanouchi, Table of n, a(n) for n = 1..200
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FORMULA
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a(n) = A270875(n) + n.
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MATHEMATICA
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Table[Length@ Select[Rest@ Subsets@ Range@ n, Total@ # == LCM @@ # &], {n, 22}] (* Michael De Vlieger, Mar 27 2016 *)
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PROG
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(PARI) a(n) = {nb = 0; S = vector(n, k, k); for (i = 0, 2^n - 1, ss = vecextract(S, i); if (sum(k=1, #ss, ss[k]) == lcm(ss), nb++); ); nb; }
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CROSSREFS
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Cf. A084422, A270875.
Sequence in context: A189404 A316681 A161793 * A188092 A188080 A048262
Adjacent sequences: A270967 A270968 A270969 * A270971 A270972 A270973
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KEYWORD
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nonn
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AUTHOR
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Michel Marcus, Mar 27 2016
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EXTENSIONS
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a(31)-a(58) from Hiroaki Yamanouchi, Mar 30 2016
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STATUS
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approved
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