A069091 -id:A069091 - cp's OEIS frontend

A160895 a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 7.

1, 63, 364, 2016, 3906, 22932, 19608, 64512, 88452, 246078, 177156, 733824, 402234, 1235304, 1421784, 2064384, 1508598, 5572476, 2613660, 7874496, 7137312, 11160828, 6728904, 23482368, 12206250, 25340742, 21493836, 39529728, 21243690, 89572392

Offset: 1

N. J. A. Sloane, Nov 19 2009

a(n) is the number of lattices L in Z^6 such that the quotient group Z^6 / L is C_nm x (C_m)^5 (and also (C_nm)^5 x C_m), for every m>=1. - Álvar Ibeas, Oct 30 2015

Enrique Pérez Herrero, Table of n, a(n) for n = 1..5000
Jin Ho Kwak and Jaeun Lee, Enumeration of graph coverings, surface branched coverings and related group theory, in Combinatorial and Computational Mathematics (Pohang, 2000), ed. S. Hong et al., World Scientific, Singapore 2001, pp. 97-161. See p. 134.
Index to Jordan function ratios J_k/J_1.

Column 6 of A263950.

Cf. A000010, A000203, A013663, A013664, A069091.

A160895 := proc(n) a := 1 ; for f in ifactors(n)[2] do p := op(1,f) ; e := op(2,f) ; a := a*p^(5*e-5)*(1+p+p^2+p^3+p^4+p^5) ; end do; a; end proc: # R. J. Mathar, Jul 10 2011

A160895[n_]:=DivisorSum[n,MoebiusMu[n/# ]*#^(7-1)/EulerPhi[n]&] (* Enrique Pérez Herrero, Oct 20 2010 *)
f[p_, e_] := p^(5*e - 5) * (p^6-1) / (p-1); ; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 30] (* Amiram Eldar, Nov 08 2022 *)

vector(50, n, sumdiv(n^5, d, if(ispower(d, 6), moebius(sqrtnint(d, 6))*sigma(n^5/d), 0))) \\ Altug Alkan, Oct 30 2014

a(n) = {f = factor(n); for (i=1, #f~, p = f[i, 1]; f[i,1] = p^(5*f[i,2]-5)*(1+p+p^2+p^3+p^4+p^5); f[i,2] = 1;); factorback(f);} \\ Michel Marcus, Nov 12 2015

a(n) = J_6(n)/J_1(n)=J_6(n)/phi(n)=A069091(n)/A000010(n), where J_k is the k-th Jordan totient function. - Enrique Pérez Herrero, Oct 20 2010
Multiplicative with a(p^e) = p^(5e-5)*(1+p+p^2+p^3+p^4+p^5). - R. J. Mathar, Jul 10 2011
For squarefree n, a(n) = A000203(n^5). - Álvar Ibeas, Oct 30 2015
From Amiram Eldar, Nov 08 2022: (Start)
Sum_{k=1..n} a(k) ~ c * n^6, where c = (1/6) * Product_{p prime} (1 + (p^5-1)/((p-1)*p^6)) = 0.3203646372... .
Sum_{k>=1} 1/a(k) = zeta(5)*zeta(6) * Product_{p prime} (1 - 2/p^6 + 1/p^11) = 1.0195114923... . (End)
a(n) = (1/n) * Sum_{d|n} mu(n/d)*sigma(d^6). - Ridouane Oudra, Apr 01 2025

Definition corrected by Enrique Pérez Herrero, Oct 20 2010

A194532 Jordan function ratio J_6(n)/J_2(n).

Original entry on oeis.org

1, 21, 91, 336, 651, 1911, 2451, 5376, 7371, 13671, 14763, 30576, 28731, 51471, 59241, 86016, 83811, 154791, 130683, 218736, 223041, 310023, 280371, 489216, 406875, 603351, 597051, 823536, 708123, 1244061, 924483, 1376256, 1343433, 1760031, 1595601, 2476656, 1875531, 2744343

Offset: 1

R. J. Mathar, Aug 28 2011

Dirichlet convolution of A000583 with the multiplicative function which starts 1, 5, 10, 0, 26, 50, 50, 0, 0, 130, 122, 0, 170, 250, 260, 0, 290,..

Robert Israel, Table of n, a(n) for n = 1..10000

Cf. A007434, A065959, A069091.

f:= proc(n) local t;
     mul(t[1]^(4*(t[2]-1))*((t[1]^2+1)^2-t[1]^2),t=ifactors(n)[2])
end proc:
map(f, [$1..100]); # Robert Israel, Jun 14 2016

JordanTotient[n_, k_: 1] := DivisorSum[n, #^k MoebiusMu[n/#] &] /; (n > 0) && IntegerQ@ n; Table[JordanTotient[n, 6]/JordanTotient[n, 2], {n, 12}] (* Michael De Vlieger, Jun 14 2016, after Enrique Pérez Herrero at A065959 *)
f[p_, e_] := p^(4*(e-1))*(p^2+p+1)*(p^2-p+1); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Oct 12 2020 *)

a(n) = {my(f = factor(n)); prod(i = 1, #f~, f[i,1]^(4*(f[i,2]-1))*(f[i,1]^2+f[i,1]+1)*(f[i,1]^2-f[i,1]+1));} \\ Amiram Eldar, Nov 05 2022

a(n) = A069091(n)/A007434(n).
Multiplicative with a(p^e) = p^(4*(e-1))*(p^2+p+1)*(p^2-p+1), e>0.
Dirichlet g.f.: zeta(s-4)*product_{primes p} (1+p^(2-s)+p^(-s)).
Sum_{k=1..n} a(k) ~ c * n^5 / 5, where c = Product_{primes p} (1 + 1/p^3 + 1/p^5) = 1.2196771388395597011492820972459808778277319864216893177353903924... - Vaclav Kotesovec, Dec 18 2019
Sum_{n>=1} 1/a(n) = (Pi^8/14175) * Product_{p prime} (1 + 1/p^2 + 1/p^4 - 1/p^6 - 1/p^8) = 1.06469274411... . - Amiram Eldar, Nov 05 2022

A343508 a(n) = Sum_{k=1..n} gcd(k, n)^6.

Original entry on oeis.org

1, 65, 731, 4162, 15629, 47515, 117655, 266372, 532905, 1015885, 1771571, 3042422, 4826821, 7647575, 11424799, 17047816, 24137585, 34638825, 47045899, 65047898, 86005805, 115152115, 148035911, 194717932, 244203145, 313743365, 388487763, 489680110, 594823349

Offset: 1

Seiichi Manyama, Apr 17 2021

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Column 6 of A343510.

Cf. A000010, A001160 (sigma_5(n)), A069091, A343520.

a[n_] := Sum[GCD[k, n]^6, {k, 1, n}]; Array[a, 50] (* Amiram Eldar, Apr 18 2021 *)
f[p_, e_] := p^(e-1)*(p^(5*e+6) - p^(5*e) - p + 1)/(p^5-1); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 50] (* Amiram Eldar, Nov 22 2022 *)

PARI
```
a(n) = sum(k=1, n, gcd(k, n)^6);
```

a(n) = sumdiv(n, d, eulerphi(n/d)*d^6);

a(n) = sumdiv(n, d, moebius(n/d)*d*sigma(d, 5));

my(N=40, x='x+O('x^N)); Vec(sum(k=1, N, eulerphi(k)*x^k*(1+57*x^k+302*x^(2*k)+302*x^(3*k)+57*x^(4*k)+x^(5*k))/(1-x^k)^7))

a(n) = Sum_{d|n} phi(n/d) * d^6.
a(n) = Sum_{d|n} mu(n/d) * d * sigma_5(d).
G.f.: Sum_{k >= 1} phi(k) * x^k * (1 + 57*x^k + 302*x^(2*k) + 302*x^(3*k) + 57*x^(4*k) + x^(5*k))/(1 - x^k)^7.
Dirichlet g.f.: zeta(s-1) * zeta(s-6) / zeta(s). - Ilya Gutkovskiy, Apr 18 2021
Sum_{k=1..n} a(k) ~ Pi^6 * n^7 / (6615*zeta(7)). - Vaclav Kotesovec, May 20 2021
Multiplicative with a(p^e) = p^(e-1)*(p^(5*e+6) - p^(5*e) - p + 1)/(p^5-1). - Amiram Eldar, Nov 22 2022
a(n) = Sum_{1 <= i_1, ..., i_6 <= n} gcd(i_1, ..., i_6, n) = Sum_{d divides n} d * J_6(n/d), where the Jordan totient function J_6(n) = A069091(n). - Peter Bala, Jan 29 2024

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

Wolfdieter Lang, Jun 22 2011

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).

			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.

Cf. A189918, A023896, A127415, A189922.

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

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).

More terms from Michel Marcus, Feb 01 2016

A255915 Triangle read by rows: T(n,k) = A239672(n)/(A239672(k) * A239672(n-k)).

Original entry on oeis.org

1, 1, 1, 1, 63, 1, 1, 728, 728, 1, 1, 4032, 46592, 4032, 1, 1, 15624, 999936, 999936, 15624, 1, 1, 45864, 11374272, 62995968, 11374272, 45864, 1, 1, 117648, 85647744, 1838132352, 1838132352, 85647744, 117648, 1, 1, 258048, 481886208, 30358831104, 117640470528

Offset: 0

Tom Edgar, Mar 10 2015

These are the generalized binomial coefficients associated with the Jordan totient function J_6 given in A069091.

Another name might be the 6-totienomial coefficients.

			The first five terms in the sixth Jordan totient function are 1, 63, 728, 4032, 15624 and so T(4,2) = 4032*728*63*1/((63*1)*(63*1)) = 46592 and T(5,3) = 15624*4032*728*63*1/((728*63*1)*(63*1)) = 999936.
The triangle begins:
1;
1, 1;
1, 63, 1;
1, 728, 728, 1;
1, 4032, 46592, 4032, 1;
1, 15624, 999936, 999936, 15624, 1;
1, 45864, 11374272, 62995968, 11374272, 45864, 1

Tom Edgar, Totienomial Coefficients, INTEGERS, 14 (2014), #A62.
Tom Edgar and Michael Z. Spivey, Multiplicative functions, generalized binomial coefficients, and generalized Catalan numbers, Journal of Integer Sequences, Vol. 19 (2016), Article 16.1.6.
Donald E. Knuth and Herbert S. Wilf, The power of a prime that divides a generalized binomial coefficient, J. Reine Angew. Math., 396:212-219, 1989.

Cf. A069091, A239672, A238453, A238688, A238743, A238754, A239633.

q=100 #change q for more rows
P=[0]+[i^6*prod([1-1/p^6 for p in prime_divisors(i)]) for i in [1..q]]
Triangle=[[prod(P[1:n+1])/(prod(P[1:k+1])*prod(P[1:(n-k)+1])) for k in [0..n]] for n in [0..len(P)-1]] #generates the triangle up to q rows.

T(n,k) = A239672(n)/(A239672(k) * A239672(n-k)).
T(n,k) = Product_{i=1..n} A069091(i)/(Product_{i=1..k} A069091(i)*Product_{i=1..n-k} A069091(i)).
T(n,k) = A069091(n)/n*(k/A069091(k)*T(n-1,k-1)+(n-k)/A069091(n-k)*T(n-1,k)).

A336488 Values taken by all the Jordan totient functions J_k(m) for k >= 1 and m >= 1.

Original entry on oeis.org

1, 2, 3, 4, 6, 7, 8, 10, 12, 15, 16, 18, 20, 22, 24, 26, 28, 30, 31, 32, 36, 40, 42, 44, 46, 48, 52, 54, 56, 58, 60, 63, 64, 66, 70, 72, 78, 80, 82, 84, 88, 92, 96, 100, 102, 104, 106, 108, 110, 112, 116, 120, 124, 126, 127, 128, 130, 132, 136, 138, 140, 144, 148

Offset: 1

Amiram Eldar, Jul 23 2020

nonn

The asymptotic density of this sequence is 0 (Rao and Murty, 1979).

First differs from A221178 at n = 75, since a(75) = J_3(6) = 182 is not a term of A221178.

R. Sita Rama Chandra Rao and G. Sri Rama Chandra Murty, On a theorem of Niven, Canadian Mathematical Bulletin, Vol 22, No. 1 (1979), pp. 113-115.

A002202 is a subsequence.
Cf. A000010, A007434, A059376, A059377, A059378, A059379, A059380, A069091, A069092, A069093, A069094, A069095, A221178.
Similar sequence: A211347.

phiQ[m_] := Select[Range[m + 1, 2 m*Product[(1 - 1/(k*Log[k]))^(-1), {k, 2, DivisorSigma[0, m]}]], EulerPhi[#] == m &, 1] != {}; jor[k_, n_] := DivisorSum[n, #^k*MoebiusMu[n/#] &]; jorval[k_, mx_] := jor[k, #] & /@ Range[Floor@Surd[mx*Zeta[k], k]]; mx = 300; Select[Union @ Flatten[{Select[Range[mx], phiQ], jorval[#, mx] & /@ Range[2, Floor[Log2[mx]]]}], # <= mx &] (* using code by Jean-François Alcover at A002202 *)

cp's OEIS Frontend

A160895 a(n) = Sum_{d|n} Moebius(n/d)*d^(b-1)/phi(n) for b = 7.

Views

Author

Keywords

Comments

Links

Crossrefs

Programs

Maple

Mathematica

PARI

PARI

Formula

Extensions

A194532 Jordan function ratio J_6(n)/J_2(n).

Views

Author

Keywords

Comments

Links

Crossrefs

Programs

Maple

Mathematica

PARI

Formula

A343508 a(n) = Sum_{k=1..n} gcd(k, n)^6.

Views

Author

Keywords

Links

Crossrefs

Programs

Mathematica

PARI

PARI

PARI

PARI

Formula

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

Views

Author

Keywords

Comments

Examples

Crossrefs

Programs

PARI

Formula

Extensions

A255915 Triangle read by rows: T(n,k) = A239672(n)/(A239672(k) * A239672(n-k)).

Views

Author

Keywords

Comments

Examples

Links

Crossrefs

Programs

Sage

Formula

A336488 Values taken by all the Jordan totient functions J_k(m) for k >= 1 and m >= 1.

Views

Author

Keywords

Comments

Links

Crossrefs

Programs

Mathematica