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A351828 Sum of the numbers <= n that are either squarefree, a divisor of n, or both. 0
1, 3, 6, 10, 11, 17, 24, 36, 33, 34, 45, 61, 58, 72, 87, 115, 104, 131, 123, 147, 144, 166, 189, 237, 214, 215, 251, 247, 244, 274, 305, 365, 338, 372, 407, 486, 444, 482, 521, 593, 562, 604, 647, 695, 701, 693, 740, 852, 789, 815, 791, 847, 844, 952, 899, 995, 956, 1014 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
a(n) = Sum_{k=1..n} k * sign(mu(k)^2 + 1 - ceiling(n/k) + floor(n/k)).
CROSSREFS
Cf. A008966.
Sequence in context: A105355 A183545 A351827 * A158975 A282876 A363775
KEYWORD
nonn
AUTHOR
Wesley Ivan Hurt, Feb 20 2022
STATUS
approved

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Last modified July 23 03:46 EDT 2024. Contains 374544 sequences. (Running on oeis4.)