Odd Mertens function












1














Let $M^*(n)$ be the "odd Mertens function", defined by $M^*(n) = sum mu(k)$ for odd $k$, $1 le k le n$.



Let $r$ be an odd number. Since $mu(r)$ is multiplicative, $mu(2r) = -mu(r)$ and $mu(4r) = mu(8r) = cdots = 0$.



So splitting $M(n) = sum_{k=1}^n mu(k)$, the standard Mertens function, by even and odd $k$, we only need to consider odd $k$ and even $k$ not divisible by 4. This gives the identity $M(n) = M^*(n) - M^*(n/2)$ or equivalently $M^*(n) = M(n) + M^*(n/2)$, so with a sublinear algorithm to calculate the Mertens function we have our odd Mertens function too.



My question: can we calculate $M^*(n)$ directly (without recursion) in sub-linear time?










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  • The effort to calculate the sum is only halved this way, this does not make the calculation sublinear , if it was not before.
    – Peter
    yesterday
















1














Let $M^*(n)$ be the "odd Mertens function", defined by $M^*(n) = sum mu(k)$ for odd $k$, $1 le k le n$.



Let $r$ be an odd number. Since $mu(r)$ is multiplicative, $mu(2r) = -mu(r)$ and $mu(4r) = mu(8r) = cdots = 0$.



So splitting $M(n) = sum_{k=1}^n mu(k)$, the standard Mertens function, by even and odd $k$, we only need to consider odd $k$ and even $k$ not divisible by 4. This gives the identity $M(n) = M^*(n) - M^*(n/2)$ or equivalently $M^*(n) = M(n) + M^*(n/2)$, so with a sublinear algorithm to calculate the Mertens function we have our odd Mertens function too.



My question: can we calculate $M^*(n)$ directly (without recursion) in sub-linear time?










share|cite|improve this question






















  • The effort to calculate the sum is only halved this way, this does not make the calculation sublinear , if it was not before.
    – Peter
    yesterday














1












1








1







Let $M^*(n)$ be the "odd Mertens function", defined by $M^*(n) = sum mu(k)$ for odd $k$, $1 le k le n$.



Let $r$ be an odd number. Since $mu(r)$ is multiplicative, $mu(2r) = -mu(r)$ and $mu(4r) = mu(8r) = cdots = 0$.



So splitting $M(n) = sum_{k=1}^n mu(k)$, the standard Mertens function, by even and odd $k$, we only need to consider odd $k$ and even $k$ not divisible by 4. This gives the identity $M(n) = M^*(n) - M^*(n/2)$ or equivalently $M^*(n) = M(n) + M^*(n/2)$, so with a sublinear algorithm to calculate the Mertens function we have our odd Mertens function too.



My question: can we calculate $M^*(n)$ directly (without recursion) in sub-linear time?










share|cite|improve this question













Let $M^*(n)$ be the "odd Mertens function", defined by $M^*(n) = sum mu(k)$ for odd $k$, $1 le k le n$.



Let $r$ be an odd number. Since $mu(r)$ is multiplicative, $mu(2r) = -mu(r)$ and $mu(4r) = mu(8r) = cdots = 0$.



So splitting $M(n) = sum_{k=1}^n mu(k)$, the standard Mertens function, by even and odd $k$, we only need to consider odd $k$ and even $k$ not divisible by 4. This gives the identity $M(n) = M^*(n) - M^*(n/2)$ or equivalently $M^*(n) = M(n) + M^*(n/2)$, so with a sublinear algorithm to calculate the Mertens function we have our odd Mertens function too.



My question: can we calculate $M^*(n)$ directly (without recursion) in sub-linear time?







number-theory algorithms mobius-function






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asked yesterday









qwr

6,55542654




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  • The effort to calculate the sum is only halved this way, this does not make the calculation sublinear , if it was not before.
    – Peter
    yesterday


















  • The effort to calculate the sum is only halved this way, this does not make the calculation sublinear , if it was not before.
    – Peter
    yesterday
















The effort to calculate the sum is only halved this way, this does not make the calculation sublinear , if it was not before.
– Peter
yesterday




The effort to calculate the sum is only halved this way, this does not make the calculation sublinear , if it was not before.
– Peter
yesterday










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