cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-7 of 7 results.

A046970 Dirichlet inverse of the Jordan function J_2 (A007434).

Original entry on oeis.org

1, -3, -8, -3, -24, 24, -48, -3, -8, 72, -120, 24, -168, 144, 192, -3, -288, 24, -360, 72, 384, 360, -528, 24, -24, 504, -8, 144, -840, -576, -960, -3, 960, 864, 1152, 24, -1368, 1080, 1344, 72, -1680, -1152, -1848, 360, 192, 1584, -2208, 24, -48, 72, 2304, 504, -2808, 24, 2880, 144, 2880, 2520, -3480, -576
Offset: 1

Views

Author

Douglas Stoll, dougstoll(AT)email.msn.com

Keywords

Comments

B(n+2) = -B(n)*((n+2)*(n+1)/(4*Pi^2))*z(n+2)/z(n) = -B(n)*((n+2)*(n+1)/(4*Pi^2)) * Sum_{j>=1} a(j)/j^(n+2).
Apart from signs also Sum_{d|n} core(d)^2*mu(n/d) where core(x) is the squarefree part of x. - Benoit Cloitre, May 31 2002

Examples

			a(3) = -8 because the divisors of 3 are {1, 3} and mu(1)*1^2 + mu(3)*3^2 = -8.
a(4) = -3 because the divisors of 4 are {1, 2, 4} and mu(1)*1^2 + mu(2)*2^2 + mu(4)*4^2 = -3.
E.g., a(15) = (3^2 - 1) * (5^2 - 1) = 8*24 = 192. - _Jon Perry_, Aug 24 2010
G.f. = x - 3*x^2 - 8*x^3 - 3*x^4 - 24*x^5 + 24*x^6 - 48*x^7 - 3*x^8 - 8*x^9 + ...
		

References

  • M. Abramowitz and I. A. Stegun, Handbook of Mathematical Functions, Dover Publications, 1965, pp. 805-811.
  • Tom M. Apostol, Introduction to Analytic Number Theory, Springer-Verlag, 1986, p. 48.

Crossrefs

Dirichlet inverse of Jordan totient function J_r(n): A023900 (r = 1), A063453(r = 3), A189922 (r = 4).

Programs

  • Haskell
    a046970 = product . map ((1 -) . (^ 2)) . a027748_row
    -- Reinhard Zumkeller, Jan 19 2012
    
  • Maple
    Jinvk := proc(n,k) local a,f,p ; a := 1 ; for f in ifactors(n)[2] do p := op(1,f) ; a := a*(1-p^k) ; end do: a ; end proc:
    A046970 := proc(n) Jinvk(n,2) ; end proc: # R. J. Mathar, Jul 04 2011
  • Mathematica
    muDD[d_] := MoebiusMu[d]*d^2; Table[Plus @@ muDD[Divisors[n]], {n, 60}] (Lopez)
    Flatten[Table[{ x = FactorInteger[n]; p = 1; For[i = 1, i <= Length[x], i++, p = p*(1 - x[[i]][[1]]^2)]; p}, {n, 1, 50, 1}]] (* Jon Perry, Aug 24 2010 *)
    a[ n_] := If[ n < 1, 0, Sum[ d^2 MoebiusMu[ d], {d, Divisors @ n}]]; (* Michael Somos, Jan 11 2014 *)
    a[ n_] := If[ n < 2, Boole[ n == 1], Times @@ (1 - #[[1]]^2 & /@ FactorInteger @ n)]; (* Michael Somos, Jan 11 2014 *)
  • PARI
    A046970(n)=sumdiv(n,d,d^2*moebius(d)) \\ Benoit Cloitre
    
  • PARI
    {a(n) = if( n<1, 0, direuler( p=2, n, (1 - X*p^2) / (1 - X))[n])}; /* Michael Somos, Jan 11 2014 */
    
  • Python
    from math import prod
    from sympy import primefactors
    def A046970(n): return prod(1-p**2 for p in primefactors(n)) # Chai Wah Wu, Sep 08 2023

Formula

Multiplicative with a(p^e) = 1 - p^2.
a(n) = Sum_{d|n} mu(d)*d^2.
abs(a(n)) = Product_{p prime divides n} (p^2 - 1). - Jon Perry, Aug 24 2010
From Wolfdieter Lang, Jun 16 2011: (Start)
Dirichlet g.f.: zeta(s)/zeta(s-2).
a(n) = J_{-2}(n)*n^2, with the Jordan function J_k(n), with J_k(1):=1. See the Apostol reference, p. 48. exercise 17. (End)
a(prime(n)) = -A084920(n). - R. J. Mathar, Aug 28 2011
G.f.: Sum_{k>=1} mu(k)*k^2*x^k/(1 - x^k). - Ilya Gutkovskiy, Jan 15 2017
a(n) = Sum_{d divides n} d * (sigma_1(d))^(-1) * sigma_1(n/d), where (sigma_1(n))^(-1) = A046692(n) denotes the Dirichlet inverse of sigma_1(n). - Peter Bala, Jan 26 2024
a(n) = A076479(n) * A322360(n). - Amiram Eldar, Feb 02 2024

Extensions

Corrected and extended by Vladeta Jovovic, Jul 25 2001
Additional comments from Wilfredo Lopez (chakotay147138274(AT)yahoo.com), Jul 01 2005

A063453 Multiplicative with a(p^e) = 1 - p^3.

Original entry on oeis.org

1, -7, -26, -7, -124, 182, -342, -7, -26, 868, -1330, 182, -2196, 2394, 3224, -7, -4912, 182, -6858, 868, 8892, 9310, -12166, 182, -124, 15372, -26, 2394, -24388, -22568, -29790, -7, 34580, 34384, 42408, 182, -50652, 48006, 57096, 868, -68920, -62244, -79506, 9310, 3224, 85162, -103822, 182
Offset: 1

Views

Author

Vladeta Jovovic, Jul 26 2001

Keywords

Comments

More generally, Dirichlet g.f. for Sum_{d|n} mu(d)*d^k, the Dirichlet inverse of the Jordan function J_k, is zeta(s)/zeta(s-k).
Apart from different signs also Sum_{d|n} core(d)^3*mu(n/d) where core(x) is the squarefree part of x. - Benoit Cloitre, May 31 2002
Dirichlet inverse of A059376. - R. J. Mathar, Jul 15 2010

References

  • T. M. Apostol, Introduction to Analytic Number Theory, Springer, 1986.

Crossrefs

Dirichlet inverse of Jordan totient function J_r(n): A023900 (r = 1), A046970(r = 2), A189922 (r = 4).
Cf. A027748.

Programs

  • Haskell
    a063453 = product . map ((1 -) . (^ 3)) . a027748_row
    -- Reinhard Zumkeller, Jan 19 2012
    
  • Maple
    Jinvk := proc(n,k) local a,f,p ; a := 1 ; for f in ifactors(n)[2] do p := op(1,f) ; a := a*(1-p^k) ; end do: a ; end proc:
    A063453 := proc(n) Jinvk(n,3) ; end proc: # R. J. Mathar, Jul 04 2011
    # second Maple program:
    a:= n-> mul(1-i[1]^3, i=ifactors(n)[2]):
    seq(a(n), n=1..48);  # Alois P. Heinz, Jan 26 2024
  • Mathematica
    a[n_] := Total[MoebiusMu[#]*#^3& /@ Divisors[n]]; Table[a[n], {n, 1, 48}] (* Jean-François Alcover, Jul 26 2011 *)
    f[p_, e_] := (1-p^3); a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Dec 08 2020 *)
  • PARI
    a(n) = sumdiv(n, d, moebius(d) * d^3); \\ Indranil Ghosh, Mar 11 2017
    
  • Python
    from math import prod
    from sympy import primefactors
    def A063453(n): return prod(1-p**3 for p in primefactors(n)) # Chai Wah Wu, Sep 08 2023

Formula

a(n) = Sum_{d|n} mu(d)*d^3.
Dirichlet g.f.: zeta(s)/zeta(s-3).
A023900(n) | a(n). - R. J. Mathar, Mar 30 2011
a(n)= product_{p|n}(1-p^3), n>=2, p prime, a(1)=1. a(n)= J_{-3}(n)*n^3, with the Jordan function J_k(n). See the Apostol reference, p. 48, exercise 17. - Wolfdieter Lang, Jun 16 2011.
G.f.: Sum_{k>=1} mu(k)*k^3*x^k/(1 - x^k). - Ilya Gutkovskiy, Jan 15 2017
a(n) = Sum_{d divides n} d * sigma_2(d)^(-1) * sigma_1(n/d), where sigma_2(n)^(-1) = A053822(n) denotes the Dirichlet inverse of sigma_2(n). - Peter Bala, Jan 26 2024

A321222 a(n) = Sum_{d|n} mu(d)*d^n.

Original entry on oeis.org

1, -3, -26, -15, -3124, 45864, -823542, -255, -19682, 9990233352, -285311670610, 2176246800, -302875106592252, 11111328602468784, 437893859848932344, -65535, -827240261886336764176, 101559568985784, -1978419655660313589123978, 99999904632567310800
Offset: 1

Views

Author

Ilya Gutkovskiy, Nov 06 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[MoebiusMu[d] d^n, {d, Divisors[n]}], {n, 20}]
    nmax = 20; Rest[CoefficientList[Series[Sum[MoebiusMu[k] (k x)^k/(1 - (k x)^k), {k, 1, nmax}], {x, 0, nmax}], x]]
    Table[Product[1 - Boole[PrimeQ[d]] d^n, {d, Divisors[n]}], {n, 20}]
  • PARI
    a(n) = sumdiv(n, d, moebius(d)*d^n) \\ Andrew Howroyd, Nov 06 2018

Formula

G.f.: Sum_{k>=1} mu(k)*(k*x)^k/(1 - (k*x)^k).
a(n) = Product_{p|n, p prime} (1 - p^n).

A334660 Dirichlet g.f.: 1 / zeta(s-4).

Original entry on oeis.org

1, -16, -81, 0, -625, 1296, -2401, 0, 0, 10000, -14641, 0, -28561, 38416, 50625, 0, -83521, 0, -130321, 0, 194481, 234256, -279841, 0, 0, 456976, 0, 0, -707281, -810000, -923521, 0, 1185921, 1336336, 1500625, 0, -1874161, 2085136, 2313441, 0, -2825761, -3111696, -3418801, 0, 0, 4477456
Offset: 1

Views

Author

Ilya Gutkovskiy, May 07 2020

Keywords

Comments

Dirichlet inverse of A000583.
Moebius transform of A189922.
Inverse Moebius transform of A053826.

Crossrefs

Programs

  • Mathematica
    Table[MoebiusMu[n] n^4, {n, 46}]

Formula

G.f. A(x) satisfies: A(x) = x - 2^4 * A(x^2) - 3^4 * A(x^3) - 4^4 * A(x^4) - ...
a(1) = 1; a(n) = -n^4 * Sum_{d|n, d < n} a(d) / d^4.
a(n) = mu(n) * n^4.
Multiplicative with a(p^e) = -p^4 if e = 1 and 0 otherwise. - Amiram Eldar, Dec 05 2022

A189923 Jordan function J_{-5}(n) multiplied by n^5.

Original entry on oeis.org

1, -31, -242, -31, -3124, 7502, -16806, -31, -242, 96844, -161050, 7502, -371292, 520986, 756008, -31, -1419856, 7502, -2476098, 96844, 4067052, 4992550, -6436342, 7502, -3124, 11510052, -242, 520986, -20511148, -23436248
Offset: 1

Views

Author

Wolfdieter Lang, Jun 16 2011

Keywords

Comments

For the Jordan function J_k see the Comtet and Apostol references.

Examples

			a(2) = a(4) = a(8) = ... = 1 - 2^5 = -31.
a(4) = mu(1)*1^5 + mu(2)*2^5 + mu(4)*4^5 = 1 - 32 + 0 = -31.
Sum identity for n=4: a(1)*(4/1)^5 + a(2)*(4/2)^5 + a(4)*(4/4)^5 = 1024 - 31*32 - 31 = 1.
		

References

  • T. M. Apostol, Introduction to Analytic Number Theory, Springer, 1986.
  • L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 199, #3.

Crossrefs

Cf. A023900, A046970, A063453, A189922, for k=-1..-4.

Programs

  • Mathematica
    a[n_] := Sum[ MoebiusMu[d]*d^5, {d, Divisors[n]}]; Table[a[n], {n, 1, 30}] (* Jean-François Alcover, Sep 03 2012 *)
    f[p_, e_] := (1-p^5); a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Dec 08 2020 *)
  • PARI
    for(n=1, 200, print1(sumdiv(n, d, moebius(d) * d^5),", ")) \\ Indranil Ghosh, Mar 11 2017
    
  • PARI
    a(n) = sumdiv(n, d, moebius(d) * d^5); \\ Michel Marcus, Jan 14 2018

Formula

a(n) = J_{-5}(n)*n^5 = Product_{p prime |n} (1-p^5), for n>=2, a(1)=1.
a(n) = Sum_{d|n} mu(d)*d^5 with the Moebius function mu = A008683.
Dirichlet g.f.: zeta(s)/zeta(s-5).
Sum identity: Sum_{d|n} a(n)*(n/d)^5 = 1 for all n>=1.
a(n) = a(rad(n)) with rad(n) = A007947(n), the squarefree kernel of n.
G.f.: Sum_{k>=1} mu(k)*k^5*x^k/(1 - x^k). - Ilya Gutkovskiy, Jan 15 2017

A322324 Square array A(n,k), n >= 1, k >= 0, read by antidiagonals: A(n,k) = Product_{p|n, p prime} (1 - p^k).

Original entry on oeis.org

1, 1, 0, 1, -1, 0, 1, -3, -2, 0, 1, -7, -8, -1, 0, 1, -15, -26, -3, -4, 0, 1, -31, -80, -7, -24, 2, 0, 1, -63, -242, -15, -124, 24, -6, 0, 1, -127, -728, -31, -624, 182, -48, -1, 0, 1, -255, -2186, -63, -3124, 1200, -342, -3, -2, 0, 1, -511, -6560, -127, -15624, 7502, -2400, -7, -8, 4, 0
Offset: 1

Views

Author

Ilya Gutkovskiy, Dec 03 2018

Keywords

Examples

			Square array begins:
  1,  1,   1,    1,     1,     1, ...
  0, -1,  -3,   -7,   -15,   -31, ...
  0, -2,  -8,  -26,   -80,  -242, ...
  0, -1,  -3,   -7,   -15,   -31, ...
  0, -4, -24, -124,  -624, -3124, ...
  0,  2,  24,  182,  1200,  7502, ...
		

Crossrefs

Columns k=0..5 give A063524, A023900, A046970, A063453, A189922, A189923.
Cf. A008683, A059379, A059380, A321222 (diagonal).

Programs

  • Mathematica
    Table[Function[k, Product[1 - Boole[PrimeQ[d]] d^k, {d, Divisors[n]}]][i - n], {i, 0, 11}, {n, 1, i}] // Flatten
    Table[Function[k, SeriesCoefficient[Sum[MoebiusMu[j] j^k x^j/(1 - x^j), {j, 1, n}], {x, 0, n}]][i - n], {i, 0, 11}, {n, 1, i}] // Flatten
    Table[Function[k, Sum[MoebiusMu[d] d^k, {d, Divisors[n]}]][i - n], {i, 0, 11}, {n, 1, i}] // Flatten
  • PARI
    T(n, k) = sumdiv(n, d, moebius(d)*d^k);
    matrix(6, 6, n, k, T(n, k-1)) \\ Michel Marcus, Dec 03 2018

Formula

G.f. of column k: Sum_{j>=1} mu(j)*j^k*x^j/(1 - x^j).
Dirichlet g.f. of column k: zeta(s)/zeta(s-k).
A(n,k) = Sum_{d|n} mu(d)*d^k.

A192000 Sum of binomial numbers A000332(k+3), with k in the reduced residue system modulo n.

Original entry on oeis.org

0, 1, 6, 16, 56, 71, 252, 296, 651, 721, 2002, 1282, 4368, 3402, 5782, 6672, 15504, 7947, 26334, 15702, 28868, 28457, 65780, 30212, 85580, 63063, 103284, 81452, 201376, 66102, 278256, 174624, 255794, 228684, 383166, 206838, 658008, 391419, 576394, 413244, 1086008
Offset: 1

Views

Author

Wolfdieter Lang, Jun 22 2011

Keywords

Comments

The reduced residue system modulo n used here is the set of numbers k from the set {0,1,...,n-1} which satisfy gcd(k,n)=1. There are phi(n) = A000010(n) such numbers k.
This is the m=4 member of a family of sequences, call them rmnS(m) (reduced mod n sum), with entries rmnS(m;n):=sum(binomial(k+m-1,m),0<=k<=n-1 with gcd(k,n)=1), m>=0, n>=1. Recall gcd(0,n)=n.
The members for m=0, 1, 2 and 3 are A000010, A023896, A127415, and A189918, respectively, where in the m=1 and 2 cases the offset for n=1 should be taken as 0 (not 1).

Examples

			a(6) = A000332(4) + A000292(8)= 1 + 70 = 71.
a(6) = (6/6!)*(6*3666*(1/3) + 5*137*2 - 182) = 71.
a(12) = A000332(4) + A000332(8) + A000332(10) + A000332(14) = 1 + 70 + 210 + 1001 = 1282.
a(12) = (12/6!)*(12*18258*(1/3) + 5*407*2 - 182) = 1282.
		

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n-1, if (gcd(n,k) == 1, binomial(k+3, 4))); \\ Michel Marcus, Feb 01 2016

Formula

a(n) = sum(A000332(k+3), 0<=k<=n-1, gcd(k,n)=1), n>=1.
a(n) = (n/6!)*(n*(6*n^3+45*n^2+110*n+90)*P(1,n) + 5*(2*n^2+9*n+11)*P(-1,n) - P(-3,n)), n>=2, with P(k,n):= J(k,n)/n^k, where J(k,n) is the Jordan function (see A000010, A007434, A059376 - A059378, A069091 - A069095).

Extensions

More terms from Michel Marcus, Feb 01 2016
Showing 1-7 of 7 results.