A129628 -id:A129628 - cp's OEIS frontend

A129354 Duplicate of A129628.

1, 3, 2, 6, 2, 6, 2, 10, 3, 6, 2, 12, 2, 6, 4, 15, 2, 9, 2, 12, 4, 6, 2, 20, 3, 6, 4, 12, 2, 12, 2, 21, 4, 6, 4, 18, 2, 6, 4, 20, 2, 12, 2, 12, 6, 6, 2, 30, 3, 9, 4, 12, 2, 12, 4, 20, 4, 6, 2, 24, 2, 6, 6, 28, 4, 12, 2, 12, 4

Offset: 1

dead

A129353 A051731 * A115361.

Original entry on oeis.org

1, 2, 1, 1, 0, 1, 3, 2, 0, 1, 1, 0, 0, 0, 1, 2, 1, 2, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 4, 3, 0, 2, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 2, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 3, 2, 3, 1, 0, 2, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1

Offset: 1

Gary W. Adamson, Apr 10 2007

The inverse Moebius transform of the first column of A115361 which is A209229 gives the first column of this sequence.

			First few rows of the triangle are:
  1;
  2, 1;
  1, 0, 1;
  3, 2, 0, 1;
  1, 0, 0, 0, 1;
  2, 1, 2, 0, 0, 1;
  1, 0, 0, 0, 0, 0, 1;
  4, 3, 0, 2, 0, 0, 0, 1;
  ...

Andrew Howroyd, Table of n, a(n) for n = 1..1275

Column 1 is A001511.
Row sums are A129628 (inverse Moebius transform of A001511).
Cf. A051731, A115361.

A129353 := proc(n,k)
        add( A051731(n,j)*A115361(j-1,k-1),j=k..n) ;
end proc: # R. J. Mathar, Jul 14 2012

T[n_, k_] := If[Mod[n, k] != 0, 0, 1 + IntegerExponent[n/k, 2]];
Table[T[n, k], {n, 1, 15}, {k, 1, n}] // Flatten (* Jean-François Alcover, Apr 08 2020, from PARI *)

T(n, k)={if(n%k, 0, 1 + valuation(n/k,2))} \\ Andrew Howroyd, Aug 04 2018

T(n,k) = A001511(n/k) for k | n, T(n,k) = 0 otherwise. - Andrew Howroyd, Aug 04 2018

A328484 Dirichlet g.f.: zeta(s)^2 / (1 - 3^(-s)).

Original entry on oeis.org

1, 2, 3, 3, 2, 6, 2, 4, 6, 4, 2, 9, 2, 4, 6, 5, 2, 12, 2, 6, 6, 4, 2, 12, 3, 4, 10, 6, 2, 12, 2, 6, 6, 4, 4, 18, 2, 4, 6, 8, 2, 12, 2, 6, 12, 4, 2, 15, 3, 6, 6, 6, 2, 20, 4, 8, 6, 4, 2, 18, 2, 4, 12, 7, 4, 12, 2, 6, 6, 8, 2, 24, 2, 4, 9, 6, 4, 12, 2, 10, 15, 4, 2, 18, 4

Offset: 1

Ilya Gutkovskiy, Oct 16 2019

Inverse Moebius transform of A051064.

Dirichlet convolution of A000005 with characteristic function of powers of 3.

Amiram Eldar, Table of n, a(n) for n = 1..10000

Cf. A000005, A051064, A129628.

Cf. A007949, A372713, A373438, A035191.

seq(add(padic[ordp](3*d, 3), d in numtheory[divisors](n)), n=1..100); # Ridouane Oudra, Sep 30 2024

Table[DivisorSum[n, IntegerExponent[3 #, 3] &], {n, 1, 85}]
nmax = 85; CoefficientList[Series[Sum[Sum[x^(i 3^j)/(1 - x^(i 3^j)), {j, 0, Floor[Log[3, nmax]] + 1}], {i, 1, nmax}], {x, 0, nmax}], x] // Rest
f[p_, e_] := If[p == 3, (e + 1)*(e + 2)/2, e + 1]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Dec 02 2020 *)

G.f.: Sum_{i>=1} Sum_{j>=0} x^(i*3^j) / (1 - x^(i*3^j)).
a(n) = Sum_{d|n} A051064(d).
Sum_{k=1..n} a(k) ~ 3*n*(log(n)/2 - log(3)/4 - 1/2 + gamma), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Oct 17 2019
Multiplicative with a(p^e) = (e+1)*(e+2)/2 if p=3, and e+1 otherwise. - Amiram Eldar, Dec 02 2020
From Ridouane Oudra, Sep 30 2024: (Start)
a(n) = Sum_{i=0..A007949(n)} tau(n/3^i).
a(n) = Sum_{d|3*n} A007949(d).
a(n) = (1/2)*A051064(n)*A372713(n).
a(n) = (1/2)*(A051064(n) + 1)*A000005(n).
a(n) = A373438(n)*A035191(n). (End)

A349693 Dirichlet convolution of the ruler function (A001511) with itself.

Original entry on oeis.org

1, 4, 2, 10, 2, 8, 2, 20, 3, 8, 2, 20, 2, 8, 4, 35, 2, 12, 2, 20, 4, 8, 2, 40, 3, 8, 4, 20, 2, 16, 2, 56, 4, 8, 4, 30, 2, 8, 4, 40, 2, 16, 2, 20, 6, 8, 2, 70, 3, 12, 4, 20, 2, 16, 4, 40, 4, 8, 2, 40, 2, 8, 6, 84, 4, 16, 2, 20, 4, 16, 2, 60, 2, 8, 6, 20, 4, 16, 2, 70

Offset: 1

Ilya Gutkovskiy, Nov 25 2021

Dirichlet convolution of A000005 with A104117. - Ridouane Oudra, Jul 23 2025

Antti Karttunen, Table of n, a(n) for n = 1..20000

Cf. A000217, A001511, A115364, A129628.

Cf. A000005, A104117, A007814, A085058, A090739, A099777, A372784, A001227, A000292,

a:= n-> (f-> add(f(d)*f(n/d), d=numtheory[divisors](n)))(k-> padic[ordp](2*k, 2)):
seq(a(n), n=1..80);  # Alois P. Heinz, Nov 25 2021

Table[Sum[IntegerExponent[2 d, 2] IntegerExponent[2 n/d, 2], {d, Divisors[n]}], {n, 1, 80}]
f[p_, e_] := If[p == 2, Binomial[e + 3, 3], e + 1]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 80] (* Amiram Eldar, Nov 25 2021 *)

A001511(n) = (1+valuation(n,2));
A349693(n) = sumdiv(n,d,A001511(n/d)*A001511(d)); \\ Antti Karttunen, Nov 25 2021

from sympy import divisor_count
def A349693(n): return divisor_count(n)*(m:=(n&-n).bit_length()+1)*(m+1)//6 # Chai Wah Wu, Jul 13 2022

Dirichlet g.f.: zeta(s)^2 * 4^s / (2^s-1)^2.
a(n) = Sum_{d|n} A001511(d) * A001511(n/d).
a(n) = Sum_{d|n} A000217(A001511(d)).
Multiplicative with a(p^e) = binomial(e+3,3) if p = 2 and e+1 otherwise. - Amiram Eldar, Nov 25 2021
Sum_{k=1..n} a(k) ~ 4*n*(log(n) - 1 + 2*gamma - 2*log(2)), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Nov 26 2021
From Ridouane Oudra, Jul 23 2025: (Start)
a(n) = Sum_{i=0..A007814(n)} (i+1)*tau(n/2^i).
a(n) = Sum_{d|n} A115364(d).
a(n) = (1/6)*A090739(n)*A085058(n-1)*A000005(n).
a(n) = (1/6)*A001511(n)*A090739(n)*A099777(n).
a(n) = (1/3)*A115364(n)*A372784(n).
a(n) = A001227(n)*A000292(A001511(n)).
a(2*n+1) = tau(2*n+1).
a(2^k*(2*n+1)) = binomial(k+3, 3)*tau(2*n+1), for k, n >= 0. (End)

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A129354 Duplicate of A129628.

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A129353 A051731 * A115361.

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A328484 Dirichlet g.f.: zeta(s)^2 / (1 - 3^(-s)).

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A349693 Dirichlet convolution of the ruler function (A001511) with itself.

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