A317946 -id:A317946 - cp's OEIS frontend

A317934 Multiplicative with a(p^n) = 2^A011371(n); denominators for certain "Dirichlet Square Roots" sequences.

1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 8, 1, 2, 1, 2, 1, 1, 1, 2, 2, 1, 2, 2, 1, 1, 1, 8, 1, 1, 1, 4, 1, 1, 1, 2, 1, 1, 1, 2, 2, 1, 1, 8, 2, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 2, 16, 1, 1, 1, 2, 1, 1, 1, 4, 1, 1, 2, 2, 1, 1, 1, 8, 8, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 8, 1, 2, 2, 4, 1, 1, 1, 2, 1

Offset: 1

Antti Karttunen, Aug 12 2018

a(n) is the denominator of certain rational valued sequences f(n), that have been defined as f(n) = (1/2) * (b(n) - Sum_{d|n, d>1, dA034444 and A037445.
Many of the same observations as given in A046644 apply also here. Note that A011371 shares with A005187 the property that A011371(x+y) <= A011371(x) + A011371(y), with equivalence attained only when A004198(x,y) = 0, and also the property that A011371(2^(k+1)) = 1 + 2*A011371(2^k).
The following list gives such pairs num(n), b(n) for which b(n) is Dirichlet convolution of num(n)/a(n).
  Numerators   Dirichlet convolution of numerator(n)/a(n) yields
  -------      -----------
  A317933      A034444
  A317941      A037445
  A317940      A046644
Expansion of Dirichlet g.f. Product_{prime} 1/(1 - 2/p^s)^(1/2) is A046643/A317934. - Vaclav Kotesovec, May 08 2025

Antti Karttunen, Table of n, a(n) for n = 1..65537
Vaclav Kotesovec, Graph - the asymptotic ratio (1000000 terms)
Wikipedia, Dirichlet convolution

Cf. A011371, A034444, A317940, A317941, A317946.
Cf. A317933, A317940, A317941 (numerator-sequences).
Cf. also A046644, A299150, A299152, A317832, A317932, A317926 (for denominator sequences of other similar constructions).
Cf. A046643, A167864, A347195.

A011371(n) = (n - hammingweight(n));
A317934(n) = factorback(apply(e -> 2^A011371(e),factor(n)[,2]));

for(n=1, 100, print1(denominator(direuler(p=2, n, 1/(1-2*X)^(1/2))[n]), ", ")) \\ Vaclav Kotesovec, May 07 2025

for(n=1, 100, print1(denominator(direuler(p=2, n, ((1+X)/(1-X))^(1/2))[n]), ", ")) \\ Vaclav Kotesovec, May 09 2025

a(n) = 2^A317946(n).
a(n) = denominator of f(n), where f(1) = 1, f(n) = (1/2) * (b(n) - Sum_{d|n, d>1, d 1, where b is A034444, A037445 or A046644 for example.
Sum_{k=1..n} A046643(k)/a(k) ~ n * sqrt(A167864*log(n)/(Pi*log(2))) * (1 + (4*(gamma - 1) + 5*log(2) - 4*A347195)/(8*log(n))), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, May 08 2025

A318315 The 2-adic valuation of A318314.

Original entry on oeis.org

0, 1, 0, 3, 0, 1, 0, 4, 1, 1, 0, 3, 0, 1, 0, 7, 0, 2, 0, 3, 0, 1, 0, 4, 1, 1, 1, 3, 0, 1, 0, 8, 0, 1, 0, 4, 0, 1, 0, 4, 0, 1, 0, 3, 1, 1, 0, 7, 1, 2, 0, 3, 0, 2, 0, 4, 0, 1, 0, 3, 0, 1, 1, 10, 0, 1, 0, 3, 0, 1, 0, 5, 0, 1, 1, 3, 0, 1, 0, 7, 3, 1, 0, 3, 0, 1, 0, 4, 0, 2, 0, 3, 0, 1, 0, 8, 0, 2, 1, 4, 0, 1, 0, 4, 0

Offset: 1

Antti Karttunen and Andrew Howroyd, Aug 29 2018

nonn

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A318314.

Cf. also A046645, A317946, A318451, A318455.

A318315(n) = valuation(A318314(n),2); \\ Needs also code from A318314.

a(n) = A007814(A318314(n)).

A318451 The 2-adic valuation of A318450.

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 1, 0, 3, 1, 1, 1, 1, 1, 2, 0, 1, 3, 1, 1, 2, 1, 1, 1, 3, 1, 4, 1, 1, 2, 1, 0, 2, 1, 2, 3, 1, 1, 2, 1, 1, 2, 1, 1, 4, 1, 1, 1, 3, 3, 2, 1, 1, 4, 2, 1, 2, 1, 1, 2, 1, 1, 4, 0, 2, 2, 1, 1, 2, 2, 1, 3, 1, 1, 4, 1, 2, 2, 1, 1, 7, 1, 1, 2, 2, 1, 2, 1, 1, 4, 2, 1, 2, 1, 2, 1, 1, 3, 4, 3, 1, 2, 1, 1, 3

Offset: 1

Antti Karttunen and Andrew Howroyd, Aug 29 2018

nonn

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A007814, A318450.

Cf. also A046645, A317946, A318315, A318455.

A318451(n) = valuation(A318450(n),2); \\ Needs also code from A318450.

a(n) = A007814(A318450(n)).

A318455 The 2-adic valuation of A318454(n).

Original entry on oeis.org

0, 1, 0, 3, 0, 1, 0, 4, 0, 1, 0, 3, 0, 1, 0, 7, 0, 1, 0, 3, 0, 1, 0, 4, 0, 1, 0, 3, 0, 1, 0, 8, 0, 1, 0, 3, 0, 1, 0, 4, 0, 1, 0, 3, 0, 1, 0, 7, 0, 1, 0, 3, 0, 1, 0, 4, 0, 1, 0, 3, 0, 1, 0, 10, 0, 1, 0, 3, 0, 1, 0, 4, 0, 1, 0, 3, 0, 1, 0, 7, 0, 1, 0, 3, 0, 1, 0, 4, 0, 1, 0, 3, 0, 1, 0, 8, 0, 1, 0, 3, 0, 1, 0, 4, 0

Offset: 1

Antti Karttunen and Andrew Howroyd, Aug 29 2018

nonn

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A001227, A007814, A318453, A318454.

Cf. also A046645, A317946, A318315, A318451.

f[1] = 1; f[n_] := f[n] = 1/2 (Sum[Mod[d, 2], {d, Divisors[n]}] - Sum[f[d] f[n/d], {d, Divisors[n][[2 ;; -2]]}]);
a[n_] := IntegerExponent[Denominator[f[n]], 2];
Array[a, 105] (* Jean-François Alcover, Sep 13 2018 *)

A318455(n) = valuation(A318454(n),2); \\ Needs also program from A318454.

a(n) = A007814(A318454(n)).

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A317934 Multiplicative with a(p^n) = 2^A011371(n); denominators for certain "Dirichlet Square Roots" sequences.

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A318315 The 2-adic valuation of A318314.

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A318451 The 2-adic valuation of A318450.

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A318455 The 2-adic valuation of A318454(n).

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