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 1-5 of 5 results.

A386749 a(n) = n*sigma_4(n).

Original entry on oeis.org

0, 1, 34, 246, 1092, 3130, 8364, 16814, 34952, 59787, 106420, 161062, 268632, 371306, 571676, 769980, 1118480, 1419874, 2032758, 2476118, 3417960, 4136244, 5476108, 6436366, 8598192, 9781275, 12624404, 14528268, 18360888, 20511178, 26179320, 28629182, 35791392, 39621252
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 01 2025

Keywords

Links

Crossrefs

Cf. A064987, A328259, A281372, A282050, A386750, A282060, A386751.
Cf. A001159, A386747, A386748.

Programs

  • Magma
    [0] cat [n*DivisorSigma(4, n): n in [1..35]]; // Vincenzo Librandi, Aug 02 2025
  • Mathematica
    Table[n*DivisorSigma[4, n], {n, 0, 50}]
nmax = 50; CoefficientList[Series[x*Sum[k^5*x^(k-1)/(1 - x^k)^2, {k, 1, nmax}], {x, 0, nmax}], x]
  • PARI
    a(n) = if (n, n*sigma(n,4), 0); \\ Michel Marcus, Aug 02 2025

Formula

G.f.: Sum_{k>=1} k^5*x^(k-1)/(1 - x^k)^2.
a(n) = n*A001159(n).
Dirichlet g.f.: zeta(s-1)*zeta(s-5). - R. J. Mathar, Aug 03 2025

A386751 a(n) = n*sigma_8(n).

Original entry on oeis.org

0, 1, 514, 19686, 263172, 1953130, 10118604, 40353614, 134744072, 387479547, 1003908820, 2357947702, 5180803992, 10604499386, 20741757596, 38449317180, 68988964880, 118587876514, 199164487158, 322687697798, 514009128360, 794401245204, 1211985118828, 1801152661486
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 01 2025

Keywords

Links

Crossrefs

Cf. A013956.
Cf. A064987, A328259, A281372, A386749, A282050, A386750, A282060.

Programs

  • Magma
    [0] cat [n*DivisorSigma(8,n): n in [1..25]]; // Vincenzo Librandi, Aug 02 2025
  • Mathematica
    Table[n*DivisorSigma[8, n], {n, 0, 40}]
nmax = 40; CoefficientList[Series[x*Sum[k^9*x^(k-1)/(1 - x^k)^2, {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=1} k^9*x^(k-1)/(1 - x^k)^2.
a(n) = n*A013956(n).
Dirichlet g.f.: zeta(s-1)*zeta(s-9). - R. J. Mathar, Aug 03 2025

A386786 a(n) = n^4*sigma_6(n).

Original entry on oeis.org

0, 1, 1040, 59130, 1065216, 9766250, 61495200, 282477650, 1090785280, 3491573931, 10156900000, 25937439242, 62986222080, 137858520410, 293776756000, 577478362500, 1116964192256, 2015993983970, 3631236888240, 6131066388122, 10403165760000, 16702903444500, 26974936811680
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 02 2025

Keywords

Links

Crossrefs

Cf. A280022, A386783, A280025, A386784, A386785, A386787, A386788.
Cf. A013954, A386750, A386777, A386780.

Programs

  • Magma
    [0] cat [n^4*DivisorSigma(6, n): n in [1..35]]; // Vincenzo Librandi, Aug 03 2025
  • Mathematica
    Table[n^4*DivisorSigma[6, n], {n, 0, 30}]
nmax = 30; CoefficientList[Series[Sum[k^4*x^k*(1 + 1013*x^k + 47840*x^(2*k) + 455192*x^(3*k) + 1310354*x^(4*k) + 1310354*x^(5*k) + 455192*x^(6*k) + 47840*x^(7*k) + 1013*x^(8*k) + x^(9*k))/(1 - x^k)^11, {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=1} k^4*x^k*(1 + 1013*x^k + 47840*x^(2*k) + 455192*x^(3*k) + 1310354*x^(4*k) + 1310354*x^(5*k) + 455192*x^(6*k) + 47840*x^(7*k) + 1013*x^(8*k) + x^(9*k))/(1 - x^k)^11.
a(n) = n^4*A013954(n).
Dirichlet g.f.: zeta(s-4)*zeta(s-10). - R. J. Mathar, Aug 03 2025

A386777 a(n) = n^2*sigma_6(n).

Original entry on oeis.org

0, 1, 260, 6570, 66576, 390650, 1708200, 5764850, 17043520, 43105851, 101569000, 214359002, 437404320, 815730890, 1498861000, 2566570500, 4363141376, 6975757730, 11207521260, 16983563402, 26007914400, 37875064500, 55733340520, 78310985810, 111975926400, 152597656875
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 02 2025

Keywords

Links

Crossrefs

Cf. A282097, A386745, A282099, A386747, A282751, A282753, A386778.
Cf. A013954, A386750.

Programs

  • Magma
    [0] cat [n^2*DivisorSigma(6, n): n in [1..35]]; // Vincenzo Librandi, Aug 04 2025
  • Mathematica
    Table[n^2*DivisorSigma[6, n], {n, 0, 30}]
nmax = 30; CoefficientList[Series[Sum[k^8*x^k*(1 + x^k)/(1 - x^k)^3, {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=1} k^8*x^k*(1 + x^k)/(1 - x^k)^3.
a(n) = n^2*A013954(n).
Dirichlet g.f.: zeta(s-2)*zeta(s-8). - R. J. Mathar, Aug 03 2025

A386780 a(n) = n^3*sigma_6(n).

Original entry on oeis.org

0, 1, 520, 19710, 266304, 1953250, 10249200, 40353950, 136348160, 387952659, 1015690000, 2357949022, 5248851840, 10604501570, 20984054000, 38498557500, 69810262016, 118587881410, 201735382680, 322687704638, 520158288000, 795376354500, 1226133491440, 1801152673630
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 02 2025

Keywords

Links

Crossrefs

Cf. A282211, A386746, A282213, A386748, A282781, A386781, A386782.
Cf. A013954, A386750, A386777.

Programs

  • Magma
    [0] cat [n^3*DivisorSigma(6, n): n in [1..35]]; // Vincenzo Librandi, Aug 04 2025
  • Mathematica
    Table[n^3*DivisorSigma[6, n], {n, 0, 30}]
nmax = 30; CoefficientList[Series[Sum[k^9*x^k*(x^(2*k) + 4*x^k + 1)/(1 - x^k)^4, {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Sum_{k>=1} k^9*x^k*(x^(2*k) + 4*x^k + 1)/(1 - x^k)^4.
a(n) = n^3*A013954(n).
Dirichlet g.f.: zeta(s-3)*zeta(s-9). - R. J. Mathar, Aug 03 2025
Showing 1-5 of 5 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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