A046645 -id:A046645 - cp's OEIS frontend

A289618 a(n) = A289617(n) - A046645(n) = A005187(A001222(n)) - A046645(n).

0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 2, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 2, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 2, 1, 2, 1, 1, 0, 2, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 2, 1, 1, 1, 2, 0, 2, 1, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 1, 0, 2, 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 2

Offset: 1

Antti Karttunen, Jul 08 2017

nonn

Antti Karttunen, Table of n, a(n) for n = 1..10000
Index entries for sequences computed from exponents in factorization of n

Cf. A046645, A289617.

Cf. A268375 (positions of zeros), A289619 (of ones).

(define (A289618 n) (- (A289617 n) (A046645 n)))

a(n) = A289617(n) - A046645(n) = A005187(A001222(n)) - A046645(n).

A305439 a(n) = A046645(n) - A007949(n); the 2-adic valuation of A317932.

Original entry on oeis.org

0, 1, 0, 3, 1, 1, 1, 4, 1, 2, 1, 3, 1, 2, 1, 7, 1, 2, 1, 4, 1, 2, 1, 4, 3, 2, 1, 4, 1, 2, 1, 8, 1, 2, 2, 4, 1, 2, 1, 5, 1, 2, 1, 4, 2, 2, 1, 7, 3, 4, 1, 4, 1, 2, 2, 5, 1, 2, 1, 4, 1, 2, 2, 10, 2, 2, 1, 4, 1, 3, 1, 5, 1, 2, 3, 4, 2, 2, 1, 8, 3, 2, 1, 4, 2, 2, 1, 5, 1, 3, 2, 4, 1, 2, 2, 8, 1, 4, 2, 6, 1, 2, 1, 5, 2

Offset: 1

Antti Karttunen, Sep 02 2018

nonn

Apart from a(1) and a(3), all other terms are positive.

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

Cf. A007814, A007949, A046645, A317932.

Cf. also A318440.

A007949(n) = valuation(n,3);
A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
A046645(n) = vecsum(apply(e -> A005187(e),factor(n)[,2]));
A305439(n) = A046645(n) - A007949(n);

a(n) = A046645(n) - A007949(n).

a(n) = A007814(A317932(n)).

A318440 a(n) = A046645(n) - A007814(n); the 2-adic valuation of A299150.

Original entry on oeis.org

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

Offset: 1

Antti Karttunen, Sep 02 2018

After two initial terms, all terms are positive.

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

Cf. A000120, A007814, A046645, A077761, A299150, A318656.

Cf. also A305439.

f[p_, e_] := (1 + Mod[p, 2])*e - DigitCount[e, 2, 1]; a[1] = 0; a[n_] := Plus @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Apr 28 2023 *)

A007814(n) = valuation(n,2);
A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
A046645(n) = vecsum(apply(e -> A005187(e),factor(n)[,2]));
A318440(n) = A046645(n) - A007814(n);

a(n) = A046645(n) - A007814(n).
a(n) = A007814(A299150(n)).
Additive with a(p^e) = (1 + (p mod 2))*e - A000120(e). - Amiram Eldar, Apr 28 2023
Sum_{k=1..n} a(k) ~ n * (log(log(n)) + B + C), where B is Mertens's constant (A077761) and C = -1 + Sum_{p prime} f(1/p) = 0.410258867603361890498..., where f(x) = -x + Sum_{k>=0} (2^(k+1)-1)*x^(2^k)/(1+x^(2^k)). - Amiram Eldar, Sep 30 2023

A318656 The 2-adic valuation of ratio A318649(n)/A318512(n); a(n) = 2*A007814(n) - A046645(n).

Original entry on oeis.org

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

Offset: 1

Antti Karttunen, Sep 02 2018

sign

Also the 2-adic valuation of ratio A318681(n)/A299150(n) [which is equal to A318649(n)/A318512(n), but not represented in lowest terms], as well as the 2-adic valuation of A318680(n)/A299150(n) = A318511(n)/A318512(n).

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

Cf. A007814, A046645, A299150, A318440, A318511, A318512, A318513, A318649, A318655, A318680, A318681.

Cf. A318654 (positions of positive terms).

A007814(n) = valuation(n,2);
A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
A046644(n) = factorback(apply(e -> 2^A005187(e),factor(n)[,2]));
A318656(n) = ((2*A007814(n))-A007814(A046644(n)));

a(n) = A318655(n) - A318513(n).
a(n) = A007814(n) - A318440(n).
a(n) = 2*A007814(n) - A046645(n) = A007814(n^2) - A046645(n).

A046644 From square root of Riemann zeta function: form Dirichlet series Sum b_n/n^s whose square is zeta function; sequence gives denominator of b_n.

Original entry on oeis.org

1, 2, 2, 8, 2, 4, 2, 16, 8, 4, 2, 16, 2, 4, 4, 128, 2, 16, 2, 16, 4, 4, 2, 32, 8, 4, 16, 16, 2, 8, 2, 256, 4, 4, 4, 64, 2, 4, 4, 32, 2, 8, 2, 16, 16, 4, 2, 256, 8, 16, 4, 16, 2, 32, 4, 32, 4, 4, 2, 32, 2, 4, 16, 1024, 4, 8, 2, 16, 4, 8, 2, 128, 2, 4, 16, 16, 4, 8

Offset: 1

N. J. A. Sloane

From Antti Karttunen, Aug 21 2018: (Start)

a(n) is the denominator of any rational-valued sequence f(n) which has been defined as f(n) = (1/2) * (b(n) - Sum_{d|n, d>1, d

Proof:

Proof is by induction. We assume as our induction hypothesis that the given multiplicative formula for A046644 (resp. additive formula for A046645) holds for all proper divisors d|n, dA046645(p) = 1. [Remark: for squares of primes, f(p^2) = (4*b(p^2) - 1)/8, thus a(p^2) = 8.]

First we note that A005187(x+y) <= A005187(x) + A005187(y), with equivalence attained only when A004198(x,y) = 0, that is, when x and y do not have any 1-bits in the shared positions. Let m = Sum_{e} A005187(e), with e ranging over the exponents in prime factorization of n.

For [case A] any n in A268388 it happens that only when d (and thus also n/d) are infinitary divisors of n will Sum_{e} A005187(e) [where e now ranges over the union of multisets of exponents in the prime factorizations of d and n/d] attain value m, which is the maximum possible for such sums computed for all divisor pairs d and n/d. For any n in A268388, A037445(n) = 2^k, k >= 2, thus A037445(n) - 2 = 2 mod 4 (excluding 1 and n from the count, thus -2). Thus, in the recursive formula above, the maximal denominator that occurs in the sum is 2^m which occurs k times, with k being an even number, but not a multiple of 4, thus the factor (1/2) in the front of the whole sum will ensure that the denominator of the whole expression is 2^m [which thus is equal to 2^A046645(n) = a(n)].

On the other hand [case B], for squares in A050376 (A082522, numbers of the form p^(2^k) with p prime and k>0), all the sums A005187(x)+A005187(y), where x+y = 2^k, 0 < x <= y < 2^k are less than A005187(2^k), thus it is the lonely "middle pair" f(p^(2^(k-1))) * f(p^(2^(k-1))) among all the pairs f(d)*f(n/d), 1 < d < n = p^(2^k) which yields the maximal denominator. Furthermore, as it occurs an odd number of times (only once), the common factor (1/2) for the whole sum will increase the exponent of 2 in denominator by one, which will be (2*A005187(2^(k-1))) + 1 = A005187(2^k) = A046645(p^(2^k)).

(End)

From Antti Karttunen, Aug 21 2018: (Start)

The following list gives a few such pairs num(n), b(n) for which b(n) is Dirichlet convolution of num(n)/a(n). Here ε stands for sequence A063524 (1, 0, 0, ...).

Numerators Dirichlet convolution of numerator(n)/a(n) yields

------- -----------

A046643 A000012

A257098 A008683

A317935 A003557

A318321 A003961

A317830 A175851

A317833 A078898

A317834 A078899

A317847 A303757

A317835 ε + A003415

A317845 ε + A001065

A317846 ε + A051953

A317936 ε + A100995

A317937 ε + A001221

A317938 ε + A001222

A317939 ε + A010051 (= A080339)

(End)

This sequence gives an upper bound for the denominators of any rational-valued sequence obtained as the "Dirichlet Square Root" of any integer-valued sequence. - Andrew Howroyd, Aug 23 2018

Antti Karttunen, Table of n, a(n) for n = 1..8192
Wikipedia, Dirichlet convolution
Index entries for sequences computed from exponents in factorization of n

Cf. A000079, A005187, A028234, A037445, A050376, A067029, A082522, A268388.
See A046643 for more details. See also A046645, A317940.
Cf. A299150, A299152, A317832, A317926, A317932, A317934 (for denominator sequences of other similar constructions).

b[1] = 1; b[n_] := b[n] = (dn = Divisors[n]; c = 1;
Do[c = c - b[dn[[i]]]*b[n/dn[[i]]], {i, 2, Length[dn] - 1}]; c/2); a[n_] := Denominator[b[n]]; a /@ Range[78] (* Jean-François Alcover, Apr 04 2011, after Maple code in A046643 *)
a18804[n_] := Sum[n EulerPhi[d]/d, {d, Divisors[n]}];
f[1] = 1; f[n_] := f[n] = 1/2 (a18804[n] - Sum[f[d] f[n/d], {d, Divisors[ n][[2 ;; -2]]}]);
a[n_] := f[n] // Denominator;
Array[a, 78] (* Jean-François Alcover, Sep 13 2018, after A318443 *)

A046643perA046644(n) = { my(c=1); if(1==n,c,fordiv(n,d, if((d>1)&&(dA046643perA046644(d)*A046643perA046644(n/d)))); (c/2)); }
A046644(n) = denominator(A046643perA046644(n)); \\ After the Maple-program given in A046643, Antti Karttunen, Jul 08 2017

A005187(n) = { my(s=n); while(n>>=1, s+=n); s; };
A046644(n) = factorback(apply(e -> 2^A005187(e),factor(n)[,2])); \\ Antti Karttunen, Aug 12 2018

for(n=1, 100, print1(denominator(direuler(p=2, n, 1/(1-X)^(1/2))[n]), ", ")) \\ Vaclav Kotesovec, May 04 2025

;; With memoization-macro definec.
(definec (A046644 n) (if (= 1 n) n (* (A000079 (A005187 (A067029 n))) (A046644 (A028234 n))))) ;; Antti Karttunen, Jul 08 2017

From Antti Karttunen, Jul 08 2017: (Start)
Multiplicative with a(p^n) = 2^A005187(n).
a(1) = 1; for n > 1, a(n) = A000079(A005187(A067029(n))) * a(A028234(n)).
a(n) = A000079(A046645(n)).
(End)
Sum_{j=1..n} A046643(j)/A046644(j) ~ n / sqrt(Pi*log(n)) * (1 + (1 - gamma/2)/(2*log(n))), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, May 04 2025

A046643 From square root of Riemann zeta function: form Dirichlet series Sum b_n/n^s whose square is zeta function; sequence gives numerator of b_n.

Original entry on oeis.org

1, 1, 1, 3, 1, 1, 1, 5, 3, 1, 1, 3, 1, 1, 1, 35, 1, 3, 1, 3, 1, 1, 1, 5, 3, 1, 5, 3, 1, 1, 1, 63, 1, 1, 1, 9, 1, 1, 1, 5, 1, 1, 1, 3, 3, 1, 1, 35, 3, 3, 1, 3, 1, 5, 1, 5, 1, 1, 1, 3, 1, 1, 3, 231, 1, 1, 1, 3, 1, 1, 1, 15, 1, 1, 3, 3, 1, 1, 1, 35, 35, 1, 1, 3, 1, 1, 1, 5, 1, 3

Offset: 1

N. J. A. Sloane, Dec 11 1999

b(n) = A046643(n)/A046644(n) is multiplicative with b(p^n) = (2n-1)!!/2^n/n!. Dirichlet g.f. of A046643(n)/A046644(n) is sqrt(zeta(x)). - Christian G. Bower, May 16 2005

That is, b(p^n) = A001147(n) / (A000079(n)*A000142(n)) = A010050(n)/A000290(A000165(n)) = (2n)!/((2^n*n!)^2). - Antti Karttunen, Jul 08 2017

			b_1, b_2, ... = 1, 1/2, 1/2, 3/8, 1/2, 1/4, 1/2, 5/16, 3/8, 1/4, 1/2, 3/16, ...

Cf. A000079, A000165, A001147, A001790, A005187, A010050, A028234, A067029.

Cf. A046644, A046645.

b := proc(n) option remember; local c,i,t1; if n = 1 then 1 else c := 1; t1 := divisors(n);
for i from 2 to nops(t1)-1 do c := c-b(t1[ i ])*b(n/t1[ i ]); od; c/2; fi; end;

b[1] = 1; b[n_] := b[n] = (dn = Divisors[n]; c = 1;
Do[c = c - b[dn[[i]]]*b[n/dn[[i]]], {i, 2, Length[dn] - 1}]; c/2); a[n_] := Numerator[b[n]]; a /@ Range[90] (* Jean-François Alcover, Apr 04 2011, after Maple version *)

A046643perA046644(n) = { my(c=1); if(1==n,c,fordiv(n,d, if((d>1)&&(dA046643perA046644(d)*A046643perA046644(n/d)))); (c/2)); }
A046643(n) = numerator(A046643perA046644(n)); \\ After Maple-program, Antti Karttunen, Jul 08 2017

for(n=1, 100, print1(numerator(direuler(p=2, n, 1/(1-X)^(1/2))[n]), ", ")) \\ Vaclav Kotesovec, May 04 2025

(define (A046643 n) (if (= 1 n) n (* (A001790 (A067029 n)) (A046643 (A028234 n)))))
;; Or, after Christian G. Bower's May 16 2005 comment:
(definec (A046643perA046644 n) (if (= 1 n) n (* (/ (A010050 (A067029 n)) (A000290 (A000165 (A067029 n)))) (A046643perA046644 (A028234 n)))))
(define (A046643 n) (numerator (A046643perA046644 n)))
(define (A046644 n) (denominator (A046643perA046644 n)))
;; Antti Karttunen, Jul 08 2017

Sum_{b|d} b(d)b(n/d) = 1. Also b_{2^j} = A001790[ j ]/2^A005187[ j ].
From Antti Karttunen, Jul 08 2017: (Start)
Multiplicative with a(p^n) = A001790(n).
a(1) = 1; for n > 1, a(n) = A001790(A067029(n)) * a(A028234(n)).
(End)
Sum_{j=1..n} A046643(j)/A046644(j) ~ n / sqrt(Pi*log(n)) * (1 + (1 - gamma/2)/(2*log(n))), where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, May 04 2025

A268375 Numbers k for which A001222(k) = A267116(k).

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 8, 9, 11, 12, 13, 16, 17, 18, 19, 20, 23, 25, 27, 28, 29, 31, 32, 37, 41, 43, 44, 45, 47, 48, 49, 50, 52, 53, 59, 61, 63, 64, 67, 68, 71, 73, 75, 76, 79, 80, 81, 83, 89, 92, 97, 98, 99, 101, 103, 107, 109, 112, 113, 116, 117, 121, 124, 125, 127, 128, 131, 137, 139, 144, 147, 148, 149, 151, 153

Offset: 1

Antti Karttunen, Feb 03 2016

Numbers k whose prime factorization k = p_1^e_1 * ... * p_m^e_m contains no pair of exponents e_i and e_j (i and j distinct) whose base-2 representations have at least one shared digit-position in which both exponents have a 1-bit.
Equivalently, numbers k such that the factors in the (unique) factorization of k into powers of squarefree numbers with distinct exponents that are powers of two, are prime powers. For example, this factorization of 90 is 10^1 * 3^2, so 90 is not included, as 10 is not prime; whereas this factorization of 320 is 5^1 * 2^2 * 2^4, so 320 is included as 5 and 2 are both prime. - Peter Munn, Jan 16 2020
A225546 maps the set of terms 1:1 onto A138302. - Peter Munn, Jan 26 2020
Equivalently, numbers k for which A064547(k) = A331591(k). - Amiram Eldar, Dec 23 2023

			12 = 2^2 * 3^1 is included in the sequence as the exponents 2 ("10" in binary) and 1 ("01" in binary) have no 1-bits in the same position, and 18 = 2^1 * 3^2 is included for the same reason.
On the other hand, 24 = 2^3 * 3^1 is NOT included in the sequence as the exponents 3 ("11" in binary) and 1 ("01" in binary) have 1-bit in the same position 0.
720 = 2^4 * 3^2 * 5^1 is included as the exponents 1, 2 and 4 ("001", "010" and "100" in binary) have no 1-bits in shared positions.
Likewise, 10! = 3628800 = 2^8 * 3^4 * 5^2 * 7^1 is included as the exponents 1, 2, 4 and 8 ("0001", "0010", "0100" and "1000" in binary) have no 1-bits in shared positions. And similarly for any term of A191555.

Antti Karttunen, Table of n, a(n) for n = 1..10000

Indices of zeros in A268374, also in A289618.
Cf. A001222, A064547, A267116, A046645, A289617, A331591.
Cf. A091862 (characteristic function), A268376 (complement).
Cf. A000961, A054753, A191555 (subsequences).
Related to A138302 via A225546.
Cf. also A318363 (a permutation).

{1}~Join~Select[Range@ 160, PrimeOmega@ # == BitOr @@ Map[Last, FactorInteger@ #] &] (* Michael De Vlieger, Feb 04 2016 *)

A289617 a(n) = A005187(A001222(n)).

Original entry on oeis.org

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

Offset: 1

Antti Karttunen, Jul 08 2017

nonn

Antti Karttunen, Table of n, a(n) for n = 1..10000
Index entries for sequences computed from exponents in factorization of n

Cf. A001222, A005187, A289618.

Cf. A268375 (positions where coincides with A046645).

a(n) = my(bn=bigomega(n)); 2*bn-hammingweight(bn); \\ Michel Marcus, Jul 10 2017

(define (A289617 n) (A005187 (A001222 n)))

a(n) = A005187(A001222(n)).

A293447 Fully additive with a(p^e) = e * A000225(PrimePi(p)), where PrimePi(n) = A000720(n) and A000225(n) = (2^n)-1.

Original entry on oeis.org

0, 1, 3, 2, 7, 4, 15, 3, 6, 8, 31, 5, 63, 16, 10, 4, 127, 7, 255, 9, 18, 32, 511, 6, 14, 64, 9, 17, 1023, 11, 2047, 5, 34, 128, 22, 8, 4095, 256, 66, 10, 8191, 19, 16383, 33, 13, 512, 32767, 7, 30, 15, 130, 65, 65535, 10, 38, 18, 258, 1024, 131071, 12, 262143, 2048, 21, 6, 70, 35, 524287, 129, 514, 23, 1048575, 9, 2097151, 4096, 17, 257, 46, 67, 4194303, 11, 12

Offset: 1

Antti Karttunen, Nov 09 2017

nonn

Original, equal definition: totally additive with a(p^e) = e * A005187(2^(PrimePi(p)-1)), where PrimePi(n) = A000720(n).

Antti Karttunen, Table of n, a(n) for n = 1..8192
Index entries for sequences computed from indices in prime factorization

Cf. A000225, A000720, A003557, A005187, A087207.

Cf. also A046645, A048675, A293442, A331591, A331740.

A005187(n) = { my(s=n); while(n>>=1, s+=n); s; }; \\ This function from Charles R Greathouse IV
A293447(n) = { my(f = factor(n)); sum(k=1, #f~, f[k, 2] * A005187(2^(primepi(f[k, 1])-1))); }

(define (A293447 n) (cond ((= 1 n) 0) (else (+ (A005187 (A087207 n)) (A293447 (A003557 n))))))
;; Alternatively:
(define (A293447 n) (if (= 1 n) 0 (+ (A005187 (A000079 (+ -1 (A061395 n)))) (A293447 (/ n (A006530 n))))))

Totally additive with a(p^e) = e * A005187(2^(PrimePi(p)-1)), where PrimePi(n) = A000720(n).
a(1) = 0, and for n > 1, a(n) = A005187(A087207(n)) + a(A003557(n)).
Other identities:
For all n >= 1, a(A293442(n)) = A046645(n).
For all n >= 2 and all k >= 0, a(n^k) = k*a(n).
For all n >= 1, a(n) >= A048675(n) >= A331740(n) >= A331591(n).

Definition simplified by Antti Karttunen, Feb 05 2020

A317946 Additive with a(p^e) = A011371(e); the 2-adic valuation of A317934(n).

Original entry on oeis.org

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

Offset: 1

Antti Karttunen, Aug 24 2018

nonn

Records are A005187, occurring at A000302 (powers of 4).

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

Cf. A000302, A005187, A011371, A317934.

Cf. also A046645.

f[p_, e_] := e - DigitCount[e, 2, 1]; a[1] = 0; a[n_] := Plus @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Jan 21 2024 *)

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

a(n) = A007814(A317934(n)).

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{p prime, k>=1} 1/(p^(2^k) - 1) = 0.63710219855356676263... . - Amiram Eldar, Jan 21 2024

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cp's OEIS Frontend

A289618 a(n) = A289617(n) - A046645(n) = A005187(A001222(n)) - A046645(n).

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A305439 a(n) = A046645(n) - A007949(n); the 2-adic valuation of A317932.

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PARI

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A318440 a(n) = A046645(n) - A007814(n); the 2-adic valuation of A299150.

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A318656 The 2-adic valuation of ratio A318649(n)/A318512(n); a(n) = 2*A007814(n) - A046645(n).

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A046644 From square root of Riemann zeta function: form Dirichlet series Sum b_n/n^s whose square is zeta function; sequence gives denominator of b_n.

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A046643 From square root of Riemann zeta function: form Dirichlet series Sum b_n/n^s whose square is zeta function; sequence gives numerator of b_n.

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Maple

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A268375 Numbers k for which A001222(k) = A267116(k).

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