A288417 -id:A288417 - cp's OEIS frontend

A109386 G.f. is the logarithm of the g.f. of A107742: Sum_{n>=1} (a(n)/n)x^n = log( Sum_{n>=0} A107742(n)x^n ).

1, 3, 7, 7, 11, 21, 15, 15, 34, 33, 23, 49, 27, 45, 77, 31, 35, 102, 39, 77, 105, 69, 47, 105, 86, 81, 142, 105, 59, 231, 63, 63, 161, 105, 165, 238, 75, 117, 189, 165, 83, 315, 87, 161, 374, 141, 95, 217, 162, 258, 245, 189, 107, 426, 253, 225, 273, 177, 119, 539, 123, 189, 510, 127, 297

Offset: 1

Paul D. Hanna, Jun 26 2005

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

Cf. A000005, A001227, A060640, A107742.

Sum_{d|n} d^k*A000593(n/d): A288417 (k=0), this sequence (k=1), A288418 (k=2), A288419 (k=3), A288420 (k=4).

a[n_] := DivisorSum[n, #*DivisorSum[#, Mod[#, 2]&]&]; Array[a, 65] (* Jean-François Alcover, Dec 23 2015 *)
f[p_, e_] := ((p + e*(p-1) - 2)*p^(e+1) + 1)/(p-1)^2; f[2, e_] := 2^(e+1) - 1; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Aug 29 2023 *)

PARI
```
a(n)=sumdiv(n,d,d*sumdiv(d,m,m%2))
```

N=66; x='x+O('x^N); /* that many terms */
c=sum(j=1, N, j*x^j);
t=log( 1/prod(j=0, N, eta(x^(2*j+1))) );
gf=serconvol(t, c);
Vec(gf) /* show terms */
/* Joerg Arndt, May 03 2008 */

a(n) = Sum_{d|n} d * Sum_{m|d} (m mod 2).
G.f.: Sum_{n>=1} a(n)/n*x^n = Sum_{j>=1} Sum_{i>=1} log(1+x^(i*j)).
From Vladeta Jovovic, Jul 05 2005:(Start)
Multiplicative with a(2^e) = 2^(e+1)-1 and a(p^e) = (p^(e+2)*(e+1)-p^(e+1)*(e+2)+1)/(p-1)^2 for p>2.
G.f.: Sum_{n>0} n*A000005(n)*x^n/(1+x^n).
G.f.: Sum_{n>0} n*A001227(n)*x^n/(1-x^n).
a(n) = A060640(n) if n is odd, else a(n) = A060640(n) - 2*A060640(n/2).
a(n) = Sum_{d|n} d*A001227(d).
a(n) = Sum_{d|n} d*A000593(n/d).
A107742(n) = (1/n)*Sum_{k=1..n} a(k)*A107742(n-k). (End)

A288418 a(n) = Sum_{d|n} d^2*A000593(n/d).

Original entry on oeis.org

1, 5, 13, 21, 31, 65, 57, 85, 130, 155, 133, 273, 183, 285, 403, 341, 307, 650, 381, 651, 741, 665, 553, 1105, 806, 915, 1210, 1197, 871, 2015, 993, 1365, 1729, 1535, 1767, 2730, 1407, 1905, 2379, 2635, 1723, 3705, 1893, 2793, 4030, 2765, 2257, 4433, 2850, 4030

Offset: 1

Seiichi Manyama, Jun 09 2017

Multiplicative because this sequence is the Dirichlet convolution of A000290 and A000593 which are both multiplicative. - Andrew Howroyd, Jul 27 2018

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

Cf. A000290, A001001, A192065, A183699.

Sum_{d|n} d^k*A000593(n/d): A288417 (k=0), A109386 (k=1), this sequence (k=2), A288419 (k=3), A288420 (k=4).

a[n_] := DivisorSum[n, Function[d, d^2*DivisorSum[n/d, If[OddQ[#], #, 0]&]] ];
Array[a, 50] (* Jean-François Alcover, Jul 03 2017 *)
f[p_, e_] := (p^(e + 1) - 1)*(p^(e + 2) - 1)/((p - 1)*(p^2 - 1)); f[2, e_] := (4^(e + 1) - 1)/3; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 50] (* Amiram Eldar, Nov 13 2022 *)

a(n) = sumdiv(n, d, d^2*sigma((n/d)>>valuation(n/d, 2))); \\ Michel Marcus, Jul 03 2017; corrected Jun 12 2022

L.g.f.: log(Product_{k>=1} (1 + x^k)^sigma(k)) = Sum_{n>=1} a(n)*x^n/n. - Ilya Gutkovskiy, Jun 19 2018
From Amiram Eldar, Nov 13 2022: (Start)
a(n) = A001001(n) for odd n.
Multiplicative with a(2^e) = (4^(e+1)-1)/3 and a(p^e) = (p^(e+1)-1)*(p^(e+2)-1)/((p-1)*(p^2-1)) for p > 2.
Sum_{k=1..n} a(k) ~ c * n^3, where c = zeta(2)*zeta(3)/4 = A183699 / 4 = 0.494326... . (End)

A288419 a(n) = Sum_{d|n} d^3*A000593(n/d).

Original entry on oeis.org

1, 9, 31, 73, 131, 279, 351, 585, 850, 1179, 1343, 2263, 2211, 3159, 4061, 4681, 4931, 7650, 6879, 9563, 10881, 12087, 12191, 18135, 16406, 19899, 22990, 25623, 24419, 36549, 29823, 37449, 41633, 44379, 45981, 62050, 50691, 61911, 68541, 76635, 68963, 97929

Offset: 1

Seiichi Manyama, Jun 09 2017

Multiplicative because this sequence is the Dirichlet convolution of A000578 and A000593 which are both multiplicative. - Andrew Howroyd, Jul 27 2018

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

Cf. A000578, A027847, A183700, A288414.

Sum_{d|n} d^k*A000593(n/d): A288417 (k=0), A109386 (k=1), A288418 (k=2), this sequence (k=3), A288420 (k=4).

f[p_, e_] := (p^(3*e+5) - (p^2+p+1)*p^(e+1) + p + 1)/((p^3-1)*(p^2-1)); f[2, e_] := (8^(e+1)-1)/7; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 50] (* Amiram Eldar, Nov 13 2022 *)

a(n)={sumdiv(n, d, (n/d)^3*sigma(d>>valuation(d,2)))} \\ Andrew Howroyd, Jul 27 2018

From Amiram Eldar, Nov 13 2022: (Start)
a(n) = A027847(n) for odd n.
Multiplicative with a(2^e) = (8^(e+1)-1)/7 and a(p^e) = (p^(3*e+5) - (p^2+p+1)*p^(e+1) + p + 1)/((p^3-1)*(p^2-1)) for p > 2.
Sum_{k=1..n} a(k) ~ c * n^4, where c = 7*Pi^4*zeta(3)/2880 = (7/32)*zeta(3)*zeta(4) = (7/32) * A183700 = 0.284596... . (End)

A288420 a(n) = Sum_{d|n} d^4*A000593(n/d).

Original entry on oeis.org

1, 17, 85, 273, 631, 1445, 2409, 4369, 6898, 10727, 14653, 23205, 28575, 40953, 53635, 69905, 83539, 117266, 130341, 172263, 204765, 249101, 279865, 371365, 394406, 485775, 558778, 657657, 707311, 911795, 923553, 1118481, 1245505, 1420163, 1520079, 1883154

Offset: 1

Seiichi Manyama, Jun 09 2017

Multiplicative because this sequence is the Dirichlet convolution of A000583 and A000593 which are both multiplicative. - Andrew Howroyd, Jul 20 2018

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

Cf. A000583, A013662, A013663, A027848, A288415.

Sum_{d|n} d^k*A000593(n/d): A288417 (k=0), A109386 (k=1), A288418 (k=2), A288419 (k=3), this sequence (k=4).

f[p_, e_] :=  (p^(4*e+7) - (p^3+p^2+p+1)*p^(e+1) + p^2 + p + 1)/(p^7 - (p^3+p^2+p+1)*p + p^2 + p + 1); f[2, e_] := (16^(e+1)-1)/15; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 50] (* Amiram Eldar, Nov 13 2022 *)

From Amiram Eldar, Nov 13 2022: (Start)
a(n) = A027848(n) for odd n.
Multiplicative with a(2^e) = (16^(e+1)-1)/15 and a(p^e) = (p^(4*e+7) - (p^3+p^2+p+1)*p^(e+1) + p^2 + p + 1)/(p^7 - (p^3+p^2+p+1)*p + p^2 + p + 1) for p > 2.
Sum_{k=1..n} a(k) ~ c * n^5, where c = Pi^4*zeta(5)/480 = (3/16)*zeta(4)*zeta(5) = 0.210429... . (End)

Keyword:mult added by Andrew Howroyd, Jul 23 2018

A288571 a(n) = Sum_{d|n} (-1)^(n/d+1)*tau(d), where tau = number of divisors (A000005).

Original entry on oeis.org

1, 1, 3, 0, 3, 3, 3, -2, 6, 3, 3, 0, 3, 3, 9, -5, 3, 6, 3, 0, 9, 3, 3, -6, 6, 3, 10, 0, 3, 9, 3, -9, 9, 3, 9, 0, 3, 3, 9, -6, 3, 9, 3, 0, 18, 3, 3, -15, 6, 6, 9, 0, 3, 10, 9, -6, 9, 3, 3, 0, 3, 3, 18, -14, 9, 9, 3, 0, 9, 9, 3, -12, 3, 3, 18, 0, 9, 9, 3, -15, 15, 3, 3, 0, 9

Offset: 1

Ilya Gutkovskiy, Aug 23 2018

Dirichlet convolution of A048272 and A000012. - Vaclav Kotesovec, Jan 13 2024

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

Cf. A000005, A001620, A007425, A017113 (positions of 0's), A048272, A288417, A317531.

with(numtheory): seq(add((-1)^(n/a+1)*tau(a),a=divisors(n)),n=1..85); # Paolo P. Lava, Aug 24 2018

Table[Sum[(-1)^(n/d + 1) DivisorSigma[0, d], {d, Divisors[n]}], {n, 85}]
nmax = 85; Rest[CoefficientList[Series[Sum[DivisorSigma[0, k] x^k/(1 + x^k), {k, 1, nmax}], {x, 0, nmax}], x]]
nmax = 85; Rest[CoefficientList[Series[Log[Product[(1 + x^k)^(DivisorSigma[0, k]/k), {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]]
f[p_, e_] := If[p == 2, (e + 1)*(2 - e)/2, (e + 1)*(e + 2)/2]; a[1] = 1; a[n_] := Times @@ (f @@@ FactorInteger[n]); Array[a, 100] (* Amiram Eldar, Oct 25 2020 *)

a(n) = sumdiv(n, d, (-1)^(n/d+1)*numdiv(d)); \\ Michel Marcus, Aug 24 2018

G.f.: Sum_{k>=1} tau(k)*x^k/(1 + x^k).
L.g.f.: log(Product_{k>=1} (1 + x^k)^(tau(k)/k)) = Sum_{n>=1} a(n)*x^n/n.
Multiplicative with a(2^e) = (e+1)*(2-e)/2, and a(p^e) = (e+1)*(e+2)/2 for an odd prime p. - Amiram Eldar, Oct 25 2020
From Amiram Eldar, Sep 14 2023: (Start)
Dirichlet g.f.: (1- 1/2^(s-1)) * zeta(s)^3.
Sum_{k=1..n} a(k) ~ log(2) * n * (log(n) + 3*gamma - 1 - log(2)/2), where gamma is Euler's constant (A001620). (End)

A318769 Expansion of e.g.f. Product_{k>=1} (1 + x^k)^(sigma(k)/k), where sigma(k) is the sum of the divisors of k.

Original entry on oeis.org

1, 1, 3, 17, 83, 639, 5749, 53227, 561273, 7216577, 94292531, 1352253561, 21657812923, 359338829407, 6460367397093, 126124578755939, 2527688612931569, 54137820027005697, 1236730462664172643, 29137619131277727457, 725282418459957414051, 18981526480933601454911

Offset: 0

Ilya Gutkovskiy, Sep 03 2018

nonn

a(n)/n! is the weigh transform of [1, 3/2, 4/3, 7/4, 6/5, ... = sums of reciprocals of divisors of 1, 2, 3, 4, 5, ...].

Vaclav Kotesovec, Table of n, a(n) for n = 0..440
Lida Ahmadi, Ricardo Gómez Aíza, and Mark Daniel Ward, A unified treatment of families of partition functions, La Matematica (2024). Preprint available as arXiv:2303.02240 [math.CO], 2023.
N. J. A. Sloane, Transforms

Cf. A000203, A017665, A017666, A168243, A192065, A288417, A305127, A318696, A318814.

with(numtheory): a := proc(n) option remember; `if`(n = 0, 1, add(add(-(-1)^(j/d)*sigma(d), d = divisors(j))*a(n-j), j = 1..n)/n) end proc; seq(n!*a(n), n = 0..20); # Vaclav Kotesovec, Sep 04 2018

nmax = 21; CoefficientList[Series[Product[(1 + x^k)^(DivisorSigma[1, k]/k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
nmax = 21; CoefficientList[Series[Exp[Sum[Sum[(-1)^(k + 1) x^(j k)/(j k (1 - x^(j k))), {j, 1, nmax}], {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[(-1)^(k/d + 1) d DivisorSigma[-1, d], {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[n! a[n], {n, 0, 21}]
nmax = 21; s = 1 + x; Do[s *= Sum[Binomial[DivisorSigma[1, k]/k, j]*x^(j*k), {j, 0, nmax/k}]; s = Expand[s]; s = Take[s, Min[nmax + 1, Exponent[s, x] + 1, Length[s]]];, {k, 2, nmax}]; Take[CoefficientList[s, x], nmax + 1] * Range[0, nmax]! (* Vaclav Kotesovec, Sep 03 2018 *)

E.g.f.: Product_{k>=1} (1 + x^k)^(A017665(k)/A017666(k)).
E.g.f.: exp(Sum_{k>=1} Sum_{j>=1} (-1)^(k+1)*x^(j*k)/(j*k*(1 - x^(j*k)))).
log(a(n)/n!) ~ sqrt(n/2) * Pi^2 / 3. - Vaclav Kotesovec, Sep 04 2018
a(n)/n! ~ c * exp(sqrt(n/2)*Pi^2/3) / n^(3/4 + log(2)/4), where c = 0.15653645678497413538057076667218805302154965061194080137... - Vaclav Kotesovec, Sep 05 2018

A130540 Triangle read by rows T(n,k) in which column k lists the terms of A000203 interspersed with (k-1) zeros, 1 <= k <= n.

Original entry on oeis.org

1, 3, 1, 4, 0, 1, 7, 3, 0, 1, 6, 0, 0, 0, 1, 12, 4, 3, 0, 0, 1, 8, 0, 0, 0, 0, 0, 1, 15, 7, 0, 3, 0, 0, 0, 1, 13, 0, 4, 0, 0, 0, 0, 0, 1, 18, 6, 0, 0, 3, 0, 0, 0, 0, 1, 12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 28, 12, 7, 4, 0, 3, 0, 0, 0, 0, 0, 1, 14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 24, 8, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 1

Offset: 1

Gary W. Adamson, Jun 03 2007

The original definition was: A127093 * A125093^(-1).
Left border = A000203, sigma(n): (1, 3, 4, 7, 6, ...). Row sums = A007429: (1, 4, 5, 11, 7, 20, 9, ...); = inverse Moebius transform applied to sigma(n); (i.e., inverse Moebius transform applied twice to natural numbers).
T(n,k) is the total number of parts congruent to 0 mod k in the partitions of n into equal parts. - Omar E. Pol, Nov 19 2019
From Omar E. Pol, Jan 01 2020: (Start)
Conjecture 1: the sum of odd-indexed terms in row n equals A327096(n).
Conjecture 2: the sum of even-indexed terms in row n equals the n-th term of the sequence formed by A000004 and A007429 interleaved.
Conjecture 3: alternating row sums give A288417. (End)

			First few rows of the triangle are:
   1;
   3,  1;
   4,  0, 1;
   7,  3, 0, 1;
   6,  0, 0, 0, 1;
  12,  4, 3, 0, 0, 1;
   8,  0, 0, 0, 0, 0, 1;
  15,  7, 0, 3, 0, 0, 0, 1;
  13,  0, 4, 0, 0, 0, 0, 0, 1;
  18,  6, 0, 0, 3, 0, 0, 0, 0, 1;
  12,  0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
  28, 12, 7, 4, 0, 3, 0, 0, 0, 0, 0, 1;
  14,  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
  24,  8, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 1;
  24,  0, 6, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1;
  31, 15, 0, 7, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 1;
...
Extended by _Omar E. Pol_, Nov 19 2019

Cf. A000203, A007429, A127093, A125093, A244051, A288417, A327096.

A127093 * A125093^(-1), as infinite lower triangular matrices.

New name and more terms from Omar E. Pol, Nov 19 2019

A318845 a(n) = Sum_{d|n} (-1)^(n/d+1) * Sum_{j|d} sigma(j), where sigma(j) = sum of divisors of j (A000203).

Original entry on oeis.org

1, 3, 6, 6, 8, 18, 10, 10, 24, 24, 14, 36, 16, 30, 48, 15, 20, 72, 22, 48, 60, 42, 26, 60, 46, 48, 82, 60, 32, 144, 34, 21, 84, 60, 80, 144, 40, 66, 96, 80, 44, 180, 46, 84, 192, 78, 50, 90, 76, 138, 120, 96, 56, 246, 112, 100, 132, 96, 62, 288, 64, 102, 240, 28, 128, 252, 70, 120, 156, 240

Offset: 1

Ilya Gutkovskiy, Sep 04 2018

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

Cf. A000203, A007429, A007430, A288417, A318768.

Table[Sum[(-1)^(n/d + 1) Sum[DivisorSigma[1, j], {j, Divisors[d]}], {d, Divisors[n]}], {n, 70}]
nmax = 70; Rest[CoefficientList[Series[Sum[DivisorSum[k, DivisorSigma[1, #] &] x^k/(1 + x^k), {k, 1, nmax}], {x, 0, nmax}], x]]
nmax = 70; Rest[CoefficientList[Series[Log[Product[(1 + x^k)^(DivisorSum[k, DivisorSigma[1, #] &]/k), {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]]
f[p_, e_] := (2*p^(e+3) - (e^2+5*e+6)*p^2 + (2*e^2+8*e+6)*p - e^2 - 3*e -2)/(2*(p-1)^3); f[2, e_] := (e+1)*(e+2)/2; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, May 26 2025 *)

a(n) = {my(f = factor(n), p , e); prod(i = 1, #f~, p = f[i, 1]; e = f[i, 2]; if(p == 2, (e+1)*(e+2)/2, (2*p^(e+3) - (e^2+5*e+6)*p^2 + (2*e^2+8*e+6)*p - e^2 - 3*e -2)/(2*(p-1)^3)));} \\ Amiram Eldar, May 26 2025

G.f.: Sum_{k>=1} A007429(k)*x^k/(1 + x^k).
L.g.f.: log(Product_{k>=1} (1 + x^k)^(A007429(k)/k)) = Sum_{n>=1} a(n)*x^n/n.
From Amiram Eldar, May 26 2025: (Start)
Multiplicative with a(2^e) = (e+1)*(e+2)/2, and a(p^e) = (2*p^(e+3) - (e^2+5*e+6)*p^2 + (2*e^2+8*e+6)*p - e^2 - 3*e -2)/(2*(p-1)^3) for an odd prime p.
Dirichlet g.f: zeta(s-1) * zeta(s)^2 * (1 - 1/2^(s-1)).
Sum_{k=1..n} a(k) ~ c * n^2, where c = Pi^6/864 = 1.112718... . (End)

A327096 Expansion of Sum_{k>=1} sigma(k) * x^k / (1 - x^(2*k)), where sigma = A000203.

Original entry on oeis.org

1, 3, 5, 7, 7, 15, 9, 15, 18, 21, 13, 35, 15, 27, 35, 31, 19, 54, 21, 49, 45, 39, 25, 75, 38, 45, 58, 63, 31, 105, 33, 63, 65, 57, 63, 126, 39, 63, 75, 105, 43, 135, 45, 91, 126, 75, 49, 155, 66, 114, 95, 105, 55, 174, 91, 135, 105, 93, 61, 245, 63, 99

Offset: 1

Ilya Gutkovskiy, Sep 13 2019

Inverse Moebius transform of A002131.

Dirichlet convolution of A000027 with A001227.

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

Cf. A000203, A001227, A002131, A007429, A026741, A060640, A109386, A133700, A288417, A300707.

nmax = 62; CoefficientList[Series[Sum[DivisorSigma[1, k] x^k/(1 - x^(2 k)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
a[n_] := Sum[Total[Select[Divisors[d], OddQ[d/#] &]], {d, Divisors[n]}]; Table[a[n], {n, 1, 62}]

a(n)={sumdiv(n, d, if(n/d%2, sigma(d)))} \\ Andrew Howroyd, Sep 13 2019

G.f.: Sum_{k>=1} A002131(k) * x^k / (1 - x^k).
G.f.: Sum_{k>=1} A001227(k) * x^k / (1 - x^k)^2.
a(n) = Sum_{d|n} A002131(d).
a(n) = Sum_{d|n} d * A001227(n/d).
a(n) = (A007429(n) + A288417(n)) / 2.
Sum_{k=1..n} a(k) ~ c * n^2, where c = Pi^4/96 = 1.01467803... (A300707). - Amiram Eldar, Oct 23 2022

A327122 Expansion of Sum_{k>=1} sigma(k) * x^k / (1 + x^(2*k)), where sigma = A000203.

Original entry on oeis.org

1, 3, 3, 7, 7, 9, 7, 15, 10, 21, 11, 21, 15, 21, 21, 31, 19, 30, 19, 49, 21, 33, 23, 45, 38, 45, 30, 49, 31, 63, 31, 63, 33, 57, 49, 70, 39, 57, 45, 105, 43, 63, 43, 77, 70, 69, 47, 93, 50, 114, 57, 105, 55, 90, 77, 105, 57, 93, 59, 147, 63, 93, 70, 127, 105

Offset: 1

Ilya Gutkovskiy, Sep 14 2019

Inverse Moebius transform of A050469.

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

Cf. A000203, A050469, A101455, A167181 (fixed points), A262209, A288417, A327123.

Cf. A072691, A175647, A243381.

nmax = 65; CoefficientList[Series[Sum[DivisorSigma[1, k] x^k/(1 + x^(2 k)), {k, 1, nmax}], {x, 0, nmax}], x] // Rest
A050469[n_] := DivisorSum[n, # &, MemberQ[{1}, Mod[n/#, 4]] &] - DivisorSum[n, # &, MemberQ[{3}, Mod[n/#, 4]] &]; a[n_] := DivisorSum[n, A050469[#] &]; Table[a[n], {n, 1, 65}]
f[p_, e_] := If[Mod[p, 4] == 1, (p^(e+2)-(e+2)*p+e+1)/(p-1)^2, (2*p^(e+2) + ((-1)^e-1)*p - ((-1)^e+1))/(2*(p^2-1))]; f[2, e_] := 2^(e+1)-1; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 70] (* Amiram Eldar, Aug 28 2023 *)

a(n) = {my(f = factor(n)); prod(i = 1, #f~, p = f[i,1]; e = f[i,2]; if(p == 2, 2^(e+1)-1, if(p%4 == 1, (p^(e+2)-(e+2)*p+e+1)/(p-1)^2, (2*p^(e+2) + ((-1)^e-1)*p - ((-1)^e+1))/(2*(p^2-1))))); } \\ Amiram Eldar, Aug 28 2023

a(n) = Sum_{d|n} A050469(d).
From Amiram Eldar, Aug 28 2023: (Start)
Multiplicative with a(2^e) = 2^(e+1)-1, and if p is an odd prime a(p^e) = (p^(e+2)-(e+2)*p+e+1)/(p-1)^2 if p == 1 (mod 4) and (2*p^(e+2) + ((-1)^e-1)*p - ((-1)^e+1))/(2*(p^2-1)) otherwise.
Sum_{k=1..n} a(k) ~ c * n^2, where c = Pi^2/12 * (A175647/A243381) = 0.753351504961... . (End)

cp's OEIS Frontend

A109386 G.f. is the logarithm of the g.f. of A107742: Sum_{n>=1} (a(n)/n)*x^n = log( Sum_{n>=0} A107742(n)*x^n ).

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A288418 a(n) = Sum_{d|n} d^2*A000593(n/d).

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A288419 a(n) = Sum_{d|n} d^3*A000593(n/d).

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A288420 a(n) = Sum_{d|n} d^4*A000593(n/d).

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A288571 a(n) = Sum_{d|n} (-1)^(n/d+1)*tau(d), where tau = number of divisors (A000005).

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A318769 Expansion of e.g.f. Product_{k>=1} (1 + x^k)^(sigma(k)/k), where sigma(k) is the sum of the divisors of k.

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A130540 Triangle read by rows T(n,k) in which column k lists the terms of A000203 interspersed with (k-1) zeros, 1 <= k <= n.

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A318845 a(n) = Sum_{d|n} (-1)^(n/d+1) * Sum_{j|d} sigma(j), where sigma(j) = sum of divisors of j (A000203).

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A109386 G.f. is the logarithm of the g.f. of A107742: Sum_{n>=1} (a(n)/n)x^n = log( Sum_{n>=0} A107742(n)x^n ).