A322581 -id:A322581 - cp's OEIS frontend

A097945 a(n) = mu(n)*phi(n) where mu(n) is the Mobius function (A008683) and phi(n) is the Euler totient function (A000010).

1, -1, -2, 0, -4, 2, -6, 0, 0, 4, -10, 0, -12, 6, 8, 0, -16, 0, -18, 0, 12, 10, -22, 0, 0, 12, 0, 0, -28, -8, -30, 0, 20, 16, 24, 0, -36, 18, 24, 0, -40, -12, -42, 0, 0, 22, -46, 0, 0, 0, 32, 0, -52, 0, 40, 0, 36, 28, -58, 0, -60, 30, 0, 0, 48, -20, -66, 0, 44, -24, -70, 0, -72, 36, 0, 0, 60, -24, -78, 0, 0, 40, -82, 0

Offset: 1

Gerald McGarvey, Sep 04 2004

Also, a(n) = mu(n)*uphi(n) where mu(n) is the Mobius function (A008683) and uphi(n) is the unitary totient function (A047994), since phi(n) = uphi(n) when n is squarefree, while mu(n) = 0 when n is not squarefree. - Franklin T. Adams-Watters, May 14 2006
Conjecture: Sum_{n>=1} mu(n)/phi(n) = Sum_{n>=1} a(n)/phi(n)^2 = 0. It is true that Sum_{n>=1} mu(n)/phi(n)^s = 0 at least for s > 1 since: phi(2)=1, phi is multiplicative, so for n's that are squarefree, the phi(n) values can be partitioned in pairs where phi(m)=phi(2m) and mu(m) = -mu(2m). So Sum_{i=1..n} mu(i)/phi(i)^s < Sum_{j=floor(n/2)..n} 1/phi(j)^s, which approaches 0 as n increases since (1) n^(1-e) < phi(n) < n for any e > 0 and n > N(e) and (2) Sum_{i..n} 1/n^s converges for s > 1. Conjecture: Sum_{n>=1} mu(n)/phi(n)^z = 0 for Re(z) > 1.
Multiplicative with a(p^1) = 1-p, a(p^e) = 0, e > 1. - Mitch Harris, May 24 2005
Row sums of triangle A143153 = a signed version of the sequence such that parity = (-) iff A008683(n) = (+); 0 or (+): (1, 1, 2, 0, 4, -2, 6, 0, 0, -4, 10, 0, 12, -6, 0, 0, 0, ...). - Gary W. Adamson, Jul 27 2008
Dirichlet inverse of A003958. - R. J. Mathar, Jul 08 2011

Alois P. Heinz, Table of n, a(n) for n = 1..10000
Wikipedia, Euler's totient function

Cf. A000010, A003958, A007947, A008683, A008966, A023900, A047994, A143153, A173557, A322581.

with(numtheory):
a:= n-> mobius(n)*phi(n):
seq(a(n), n=1..100);  # Alois P. Heinz, Aug 06 2012

Table[ MoebiusMu[n]EulerPhi[n], {n, 85}] (* Robert G. Wilson v, Sep 06 2004 *)

a(n)=moebius(n)*eulerphi(n) \\ Charles R Greathouse IV, Feb 21 2013

for(n=1, 100, print1(direuler(p=2, n, (1 - p*X + X))[n], ", ")) \\ Vaclav Kotesovec, Jun 14 2020

Dirichlet g.f.: Product_{primes p} (1-p^(1-s)+p^(-s)). - R. J. Mathar, Aug 29 2011
Sum_{d|n} abs(a(d)) = rad(n) = A007947(n). - Rémy Sigrist, Nov 05 2017
Sum_{k=1..n} abs(a(k)) ~ c * n^2, where c = A065464/2 = (1/2) * Product_{primes p} (1 - 2/p^2 + 1/p^3) = 0.21412475283854722... Equivalently, c = A065463 * 3 / Pi^2. - Vaclav Kotesovec, Jun 14 2020
From Antti Karttunen, Aug 20 2021: (Start)
a(n) = mu(n)*A000010(n) = mu(n)*A003958(n) = mu(n)*A047994(n) = mu(n)*A173557(n), where mu is Möbius mu function (A008683).
a(n) = A008966(n) * A023900(n) = abs(mu(n)) * A023900(n).
a(n) = A322581(n) - A003958(n).
(End)

More terms from Robert G. Wilson v, Sep 06 2004

Edited by N. J. A. Sloane, May 20 2006

A322582 a(n) = n - A003958(n), where A003958 is fully multiplicative with a(p) = (p-1).

Original entry on oeis.org

0, 1, 1, 3, 1, 4, 1, 7, 5, 6, 1, 10, 1, 8, 7, 15, 1, 14, 1, 16, 9, 12, 1, 22, 9, 14, 19, 22, 1, 22, 1, 31, 13, 18, 11, 32, 1, 20, 15, 36, 1, 30, 1, 34, 29, 24, 1, 46, 13, 34, 19, 40, 1, 46, 15, 50, 21, 30, 1, 52, 1, 32, 39, 63, 17, 46, 1, 52, 25, 46, 1, 68, 1, 38, 43, 58, 17, 54, 1, 76, 65, 42, 1, 72, 21, 44, 31, 78, 1

Offset: 1

Antti Karttunen, Dec 17 2018

nonn

a(p*(n/p)) - (n/p) = (p-1)*a(n/p) holds for all prime divisors p of n, which can be seen by expanding the left hand side as p*(n/p) - A003958(p*(n/p)) - (n/p) = (p-1)*(n/p) - (p-1)*A003958(n/p) = (p-1)*((n/p) - A003958(n/p)) = (p-1)*a(n/p). This shows that this sequence gives a lower limit for arithmetic derivative (A003415) in the same way as A348507 gives an upper limit for it. - Antti Karttunen, Nov 07 2021

With n = Product_{i=1..k} p_i the prime factorization of n, if one constructs for each i a test with a probability of success equal to 1/p_i, and if the tests are independent, then a(n)/n is the probability that at least one of the k tests succeeds. - Luc Rousseau, Jan 14 2023

Antti Karttunen, Table of n, a(n) for n = 1..16384

Cf. A003415, A003958, A322581, A348507, A348928 [= gcd(n,a(n))], A348975 (difference from the arithmetic derivative).
Cf. A349139, A348980, A348981, A348982, A348983 (Dirichlet convolutions with other sequences).
Cf. A168065 (gives the arithmetic mean of this and A348507), A168066.

a[1] = 0; a[n_] := n - Times @@ ((First[#] - 1)^Last[#] & /@ FactorInteger[n]); Array[a, 60] (* Amiram Eldar, Dec 17 2018 *)

A003958(n) = { my(f = factor(n)); for(i=1, #f~, f[i, 1]--); factorback(f); };
A322582(n) = (n-A003958(n));

A020639(n) = if(1==n, n, (factor(n)[1, 1]));
A322582(n) = { my(s=0, m=1, spf); while(n>1, spf = A020639(n); n /= spf; s += m*n; m *= (spf-1)); (s); }; \\ (Compare to the similar programs given in A003415 and A348507) - Antti Karttunen, Nov 07 2021

a(n) = n - A003958(n).
From Antti Karttunen, Nov 07 2021: (Start)
a(n) = A003415(n) - A348975(n).
For all n >= 1, a(n) <= A003415(n) <= A348507(n).
For n > 1, a(n) = a(A032742(n))*(A020639(n)-1) + A032742(n). [See the comment above and compare with Reinhard Zumkeller's May 09 2011 formula for A003415]
(End)

A323364 Sum of Dedekind's psi, A001615, and its Dirichlet inverse, A323363.

Original entry on oeis.org

2, 0, 0, 9, 0, 24, 0, 9, 16, 36, 0, 12, 0, 48, 48, 27, 0, 24, 0, 18, 64, 72, 0, 60, 36, 84, 32, 24, 0, 0, 0, 45, 96, 108, 96, 84, 0, 120, 112, 90, 0, 0, 0, 36, 48, 144, 0, 84, 64, 72, 144, 42, 0, 120, 144, 120, 160, 180, 0, 216, 0, 192, 64, 99, 168, 0, 0, 54, 192, 0, 0, 132, 0, 228, 96, 60, 192, 0, 0, 126, 112, 252, 0, 288, 216, 264, 240, 180, 0

Offset: 1

Antti Karttunen, Jan 13 2019

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384

Cf. A001615, A323363.

Cf. also A319340, A322581, A323365, A323372, A323399.

A001615(n) = (n * sumdivmult(n, d, issquarefree(d)/d)); \\ From A001615
A323363(n) = if(1==n,1,-sumdiv(n,d,if(dA001615(n/d)*A323363(d),0)));
A323364(n) = (A001615(n) + A323363(n));

A349126 Sum of A064989 and its Dirichlet inverse, where A064989 is multiplicative with a(2^e) = 1 and a(p^e) = prevprime(p)^e for odd primes p.

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 1, 4, 6, 0, 2, 0, 10, 12, 1, 0, 4, 0, 3, 20, 14, 0, 2, 9, 22, 8, 5, 0, 0, 0, 1, 28, 26, 30, 4, 0, 34, 44, 3, 0, 0, 0, 7, 12, 38, 0, 2, 25, 9, 52, 11, 0, 8, 42, 5, 68, 46, 0, 6, 0, 58, 20, 1, 66, 0, 0, 13, 76, 0, 0, 4, 0, 62, 18, 17, 70, 0, 0, 3, 16, 74, 0, 10, 78, 82, 92, 7, 0, 12, 110, 19, 116

Offset: 1

Antti Karttunen, Nov 13 2021

Question: Are all terms nonnegative?

Answer: All terms certainly are >= 0. See Sebastian Karlsson's Nov 13 2021 multiplicative formula for A349125. - Antti Karttunen, Apr 20 2022

Antti Karttunen, Table of n, a(n) for n = 1..20000
Index entries for sequences computed from indices in prime factorization

Cf. A001248, A064989, A030059, A030229, A280076, A349125.
Cf. also A322581, A349135.
Coincides with A349349 on odd numbers.

f1[p_, e_] := If[p == 2, 1, NextPrime[p, -1]^e]; a1[1] = 1; a1[n_] := Times @@ f1 @@@ FactorInteger[n]; f2[p_, e_] := If[e == 1, If[p == 2, -1, -NextPrime[p, -1]], 0]; a2[1] = 1; a2[n_] := Times @@ f2 @@@ FactorInteger[n]; a[n_] := a1[n] + a2[n]; Array[a, 100] (* Amiram Eldar, Nov 13 2021 *)

A349126(n) = (A064989(n)+A349125(n)); \\ Needs also code from A349125.

A349126(n) = if(1==n,2,-sumdiv(n, d, if(1==d||n==d,0,A064989(d)*A349125(n/d)))); \\ (This demonstrates the "cut convolution" formula) - Antti Karttunen, Nov 13 2021

a(n) = A064989(n) + A349125(n).
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A064989(d) * A349125(n/d).
For all n >= 1, a(A030059(n)) = 0, a(A030229(n)) = 2*A064989(A030229(n)).
For all n >= 1, a(A001248(n)) = A280076(n).

A323399 Sum of Jordan function J_2(n), A007434 and its Dirichlet inverse, A046970.

Original entry on oeis.org

2, 0, 0, 9, 0, 48, 0, 45, 64, 144, 0, 120, 0, 288, 384, 189, 0, 240, 0, 360, 768, 720, 0, 408, 576, 1008, 640, 720, 0, 0, 0, 765, 1920, 1728, 2304, 888, 0, 2160, 2688, 1224, 0, 0, 0, 1800, 1920, 3168, 0, 1560, 2304, 1872, 4608, 2520, 0, 1968, 5760, 2448, 5760, 5040, 0, 1728, 0, 5760, 3840, 3069, 8064, 0, 0, 4320, 8448, 0, 0, 3480, 0, 8208, 4992, 5400

Offset: 1

Antti Karttunen, Jan 13 2019

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384

Cf. A007434, A046970.

Cf. also A319340, A322581, A323364.

A007434(n) = sumdiv(n, d, d*d*moebius(n/d));
A046970(n) = if(1==n,n,my(f=factor(n)); for(i=1, #f~, f[i,1] = 1-(f[i,1]^2)); factorback(f[,1]));
A323399(n) = (A007434(n) + A046970(n));

a(n) = A007434(n) + A046970(n).

A323403 Sum of sigma and its Dirichlet inverse: a(n) = A000203(n) + A046692(n).

Original entry on oeis.org

2, 0, 0, 9, 0, 24, 0, 15, 16, 36, 0, 20, 0, 48, 48, 31, 0, 30, 0, 30, 64, 72, 0, 60, 36, 84, 40, 40, 0, 0, 0, 63, 96, 108, 96, 97, 0, 120, 112, 90, 0, 0, 0, 60, 60, 144, 0, 124, 64, 78, 144, 70, 0, 120, 144, 120, 160, 180, 0, 216, 0, 192, 80, 127, 168, 0, 0, 90, 192, 0, 0, 195, 0, 228, 104, 100, 192, 0, 0, 186, 121, 252, 0, 288, 216, 264, 240, 180, 0, 288

Offset: 1

Antti Karttunen, Jan 15 2019

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384
Index entries for sequences related to sigma(n)

Cf. A000203, A046692.

Cf. also A319340, A322581, A323364, A323399, A323408.

up_to = 16384;
DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA047994(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^f[2, i])-1); };
v046692 = DirInverse(vector(up_to,n,sigma(n)));
A046692(n) = v046692[n];
A323403(n) = (sigma(n)+A046692(n));

a(n) = A000203(n) + A046692(n).

A323408 Sum of unitary phi and its Dirichlet inverse: a(n) = A047994(n) + A323407(n).

Original entry on oeis.org

2, 0, 0, 1, 0, 4, 0, 5, 4, 8, 0, 10, 0, 12, 16, 15, 0, 12, 0, 20, 24, 20, 0, 18, 16, 24, 24, 30, 0, 0, 0, 35, 40, 32, 48, 32, 0, 36, 48, 36, 0, 0, 0, 50, 48, 44, 0, 30, 36, 32, 64, 60, 0, 28, 80, 54, 72, 56, 0, 8, 0, 60, 72, 71, 96, 0, 0, 80, 88, 0, 0, 64, 0, 72, 64, 90, 120, 0, 0, 60, 88, 80, 0, 12, 128, 84, 112, 90, 0, 16, 144, 110, 120

Offset: 1

Antti Karttunen, Jan 15 2019

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384

Cf. A047994, A323407.

Cf. also A319340, A322581, A323364, A323399, A323403.

up_to = 65537;
DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA047994(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^f[2, i])-1); };
v323407 = DirInverse(vector(up_to,n,A047994(n)));
A323407(n) = v323407[n];
A323408(n) = (A047994(n) + A323407(n));

A349912 Sum of A336466 and its Dirichlet inverse, where A336466 is fully multiplicative with a(p) = oddpart(p-1).

Original entry on oeis.org

2, 0, 0, 1, 0, 2, 0, 1, 1, 2, 0, 1, 0, 6, 2, 1, 0, 1, 0, 1, 6, 10, 0, 1, 1, 6, 1, 3, 0, 0, 0, 1, 10, 2, 6, 1, 0, 18, 6, 1, 0, 0, 0, 5, 1, 22, 0, 1, 9, 1, 2, 3, 0, 1, 10, 3, 18, 14, 0, 1, 0, 30, 3, 1, 6, 0, 0, 1, 22, 0, 0, 1, 0, 18, 1, 9, 30, 0, 0, 1, 1, 10, 0, 3, 2, 42, 14, 5, 0, 1, 18, 11, 30, 46, 18, 1, 0, 9, 5, 1

Offset: 1

Antti Karttunen, Dec 08 2021

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384

Cf. A336466 (also a quadrisection of this sequence), A349911.

Cf. also A322581.

f[p_, e_] := ((p-1)/2^IntegerExponent[p-1, 2])^e; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; sinv[1] = 1; sinv[n_] := sinv[n] = -DivisorSum[n, sinv[#] * s[n/#] &, # < n &]; a[n_] := s[n] + sinv[n]; Array[a, 100] (* Amiram Eldar, Dec 08 2021 *)

A000265(n) = (n>>valuation(n,2));
A336466(n) = { my(f=factor(n)); prod(k=1,#f~,A000265(f[k,1]-1)^f[k,2]); };
memoA349911 = Map();
A349911(n) = if(1==n,1,my(v); if(mapisdefined(memoA349911,n,&v), v, v = -sumdiv(n,d,if(dA336466(n/d)*A349911(d),0)); mapput(memoA349911,n,v); (v)));
A349912(n) = (A336466(n)+A349911(n));

a(n) = A336466(n) + A349911(n).
a(1) = 2, and for n > 1, a(n) = -Sum_{d|n, 1A336466(d) * A349911(n/d).
a(4*n) = A336466(n).

cp's OEIS Frontend

A097945 a(n) = mu(n)*phi(n) where mu(n) is the Mobius function (A008683) and phi(n) is the Euler totient function (A000010).

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A322582 a(n) = n - A003958(n), where A003958 is fully multiplicative with a(p) = (p-1).

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A323364 Sum of Dedekind's psi, A001615, and its Dirichlet inverse, A323363.

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A349126 Sum of A064989 and its Dirichlet inverse, where A064989 is multiplicative with a(2^e) = 1 and a(p^e) = prevprime(p)^e for odd primes p.

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A323399 Sum of Jordan function J_2(n), A007434 and its Dirichlet inverse, A046970.

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A323403 Sum of sigma and its Dirichlet inverse: a(n) = A000203(n) + A046692(n).

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A323408 Sum of unitary phi and its Dirichlet inverse: a(n) = A047994(n) + A323407(n).

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A349912 Sum of A336466 and its Dirichlet inverse, where A336466 is fully multiplicative with a(p) = oddpart(p-1).

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