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A270970 Number of subsets of {1,...,n} with sum of elements equal to least common multiple of elements. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Similar to A270875 but also counts singletons, the trivial solutions.

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 1..200

FORMULA

a(n) = A270875(n) + n.

MATHEMATICA

Table[Length@ Select[Rest@ Subsets@ Range@ n, Total@ # == LCM @@ # &], {n, 22}] (* Michael De Vlieger, Mar 27 2016 *)

PROG

(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; }

CROSSREFS

Cf. A084422, A270875.

Sequence in context: A189404 A316681 A161793 * A188092 A188080 A048262

Adjacent sequences:  A270967 A270968 A270969 * A270971 A270972 A270973

KEYWORD

nonn

AUTHOR

Michel Marcus, Mar 27 2016

EXTENSIONS

a(31)-a(58) from Hiroaki Yamanouchi, Mar 30 2016

STATUS

approved

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Last modified June 30 08:45 EDT 2022. Contains 354919 sequences. (Running on oeis4.)