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.

A282060 Coefficients in q-expansion of E_4*(E_2*E_4 - E_6)/720, where E_2, E_4, E_6 are the Eisenstein series shown in A006352, A004009, A013973, respectively.

Original entry on oeis.org

0, 1, 258, 6564, 66052, 390630, 1693512, 5764808, 16909320, 43066413, 100782540, 214358892, 433565328, 815730734, 1487320464, 2564095320, 4328785936, 6975757458, 11111134554, 16983563060, 25801892760, 37840199712, 55304594136, 78310985304, 110992776480
Offset: 0

Views

Author

Seiichi Manyama, Feb 05 2017

Keywords

Comments

Multiplicative because A013955 is. - Andrew Howroyd, Jul 25 2018

Examples

			a(6) = 1^8*6^1 + 2^8*3^1 + 3^8*2^1 + 6^8*1^1 = 1693512.
		

Crossrefs

Cf. A064987 (phi_{2, 1}), A281372 (phi_{4, 1}), A282050 (phi_{6, 1}), this sequence (phi_{8, 1}).
Cf. A006352 (E_2), A004009 (E_4), A013973 (E_6), A282101 (E_2*E_4^2), A013974 (E_4*E_6 = E_10).

Programs

  • Mathematica
    terms = 25;
    E2[x_] = 1 - 24*Sum[k*x^k/(1 - x^k), {k, 1, terms}];
    E4[x_] = 1 + 240*Sum[k^3*x^k/(1 - x^k), {k, 1, terms}];
    E6[x_] = 1 - 504*Sum[k^5*x^k/(1 - x^k), {k, 1, terms}];
    E4[x]*(E2[x]*E4[x] - E6[x])/720 + O[x]^terms // CoefficientList[#, x]& (* Jean-François Alcover, Feb 26 2018 *)
    Table[n * DivisorSigma[7, n], {n, 0, 24}] (* Amiram Eldar, Sep 06 2023 *)
    nmax = 40; CoefficientList[Series[x*Sum[k^8*x^(k-1)/(1 - x^k)^2, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Aug 01 2025 *)
  • PARI
    a(n) = if(n < 1, 0, n*sigma(n, 7)) \\ Andrew Howroyd, Jul 25 2018

Formula

G.f.: phi_{8, 1}(x) where phi_{r, s}(x) = Sum_{n, m>0} m^r * n^s * x^{m*n}.
a(n) = (A282101(n) - A013974(n))/720. - Seiichi Manyama, Feb 10 2017
If p is a prime, a(p) = p^8 + p = A196288(p). - Seiichi Manyama, Feb 10 2017
a(n) = n*A013955(n) for n > 0. - Seiichi Manyama, Feb 18 2017
Sum_{k=1..n} a(k) ~ zeta(8) * n^9 / 9. - Amiram Eldar, Sep 06 2023
From Amiram Eldar, Oct 30 2023: (Start)
Multiplicative with a(p^e) = p^e * (p^(7*e+7)-1)/(p^7-1).
Dirichlet g.f.: zeta(s-1)*zeta(s-8). (End)
G.f. Sum_{k>=1} k^8*x^(k-1)/(1 - x^k)^2. - Vaclav Kotesovec, Aug 01 2025

A196289 a(n) = n^9 - n.

Original entry on oeis.org

0, 0, 510, 19680, 262140, 1953120, 10077690, 40353600, 134217720, 387420480, 999999990, 2357947680, 5159780340, 10604499360, 20661046770, 38443359360, 68719476720, 118587876480, 198359290350, 322687697760, 511999999980, 794280046560, 1207269217770, 1801152661440, 2641807540200
Offset: 0

Views

Author

Vincenzo Librandi, Oct 01 2011

Keywords

Crossrefs

Programs

  • Magma
    [n^9-n: n in [0..30]];
    
  • Mathematica
    Table[n^9 - n, {n, 0, 40}] (* and *) LinearRecurrence[{10, -45, 120, -210, 252, -210, 120, -45, 10, -1}, {0, 0, 510, 19680, 262140, 1953120, 10077690, 40353600, 134217720, 387420480}, 40] (* Vladimir Joseph Stephan Orlovsky, Feb 21 2012 *)
  • PARI
    a(n)=n^9-n \\ Charles R Greathouse IV, Nov 21 2011

Formula

G.f.: 30*x^2*(17+486*x+2943*x^2+5204*x^3+2943*x^4+486*x^5+17*x^6) / (x-1)^10 . - R. J. Mathar, Oct 13 2011

A196290 a(n) = n^9 + n.

Original entry on oeis.org

0, 2, 514, 19686, 262148, 1953130, 10077702, 40353614, 134217736, 387420498, 1000000010, 2357947702, 5159780364, 10604499386, 20661046798, 38443359390, 68719476752, 118587876514, 198359290386, 322687697798, 512000000020, 794280046602, 1207269217814, 1801152661486, 2641807540248
Offset: 0

Views

Author

Vincenzo Librandi, Oct 01 2011

Keywords

Crossrefs

Programs

Formula

G.f.: 2*x*(1+247*x+7318*x^2+44089*x^3+78130*x^4+44089*x^5+7318*x^6+247*x^7+x^8) / (x-1)^10 . a(n) = 2*A168116(n). - R. J. Mathar, Oct 13 2011
a(n) = 10*a(n-1) - 45*a(n-2) + 120*a(n-3) - 210*a(n-4) + 252*a(n-5) - 210*a(n-6) + 120*a(n-7) - 45*a(n-8) + 10*a(n-9) - a(n-10). - Wesley Ivan Hurt, May 04 2023

A196291 a(n) = n^10 - n.

Original entry on oeis.org

0, 0, 1022, 59046, 1048572, 9765620, 60466170, 282475242, 1073741816, 3486784392, 9999999990, 25937424590, 61917364212, 137858491836, 289254654962, 576650390610, 1099511627760, 2015993900432, 3570467226606, 6131066257782, 10239999999980, 16679880978180, 26559922791402, 41426511213626
Offset: 0

Views

Author

Vincenzo Librandi, Oct 01 2011

Keywords

Crossrefs

Programs

  • Magma
    [n^10-n: n in [0..30]];
    
  • Mathematica
    Table[n^10 - n, {n, 0, 40}] (* and *) LinearRecurrence[{11, -55, 165, -330, 462, -462, 330, -165, 55, -11, 1}, {0, 0, 1022, 59046, 1048572, 9765620, 60466170, 282475242, 1073741816, 3486784392, 9999999990}, 40] (* Vladimir Joseph Stephan Orlovsky, Feb 21 2012 *)
  • PARI
    a(n)=n^10-n \\ Charles R Greathouse IV, Nov 22 2011

A196292 a(n) = n^10 + n.

Original entry on oeis.org

0, 2, 1026, 59052, 1048580, 9765630, 60466182, 282475256, 1073741832, 3486784410, 10000000010, 25937424612, 61917364236, 137858491862, 289254654990, 576650390640, 1099511627792, 2015993900466, 3570467226642, 6131066257820, 10240000000020, 16679880978222, 26559922791446
Offset: 0

Views

Author

Vincenzo Librandi, Oct 01 2011

Keywords

Crossrefs

Programs

  • Magma
    [n^10+n: n in [0..30]];

Formula

a(n) = 2 * A168118(n). - Alois P. Heinz, Jul 28 2025
Showing 1-5 of 5 results.