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 1-6 of 6 results.

A107658 Coefficients of 6th root of theta series of Coxeter-Todd lattice K_{12} (see A004010).

Original entry on oeis.org

1, 0, 126, 672, -36288, -413280, 15087870, 275661792, -6846707322, -186737716704, 3093536396160, 126405712075104, -1274633447433024, -84873293805379968, 385697576191762044, 56246329449791661600, 31646424393253329408
Offset: 0

Views

Author

N. J. A. Sloane and Michael Somos, Jun 07 2005

Keywords

Crossrefs

Cf. A004010.

Programs

  • Mathematica
    terms = 17; QP = QPochhammer; s = ((QP[q]^18*(4 - 4*(1 + (9*q*QP[q^9]^3) / QP[q]^3)^3 + 3*(1 + (9*q*QP[q^9]^3)/QP[q]^3)^6))/(3*QP[q^3]^6))^(1/6) + O[q]^terms; CoefficientList[s, q] (* Jean-François Alcover, Jul 08 2017, after Michael Somos *)

A320686 Inverse Euler transform of A004010.

Original entry on oeis.org

0, 756, 4032, -265734, -2987712, 120604680, 2176735680, -58263976134, -1563340453248, 27722120100948, 1105815958027200, -12029301541618956, -769283790627284352, 3952625120472002580, 525306588856752370752, 41570815360527775098, -351118365555207656907648
Offset: 1

Views

Author

Seiichi Manyama, Oct 19 2018

Keywords

Comments

a(n) is a multiple of 6.

Examples

			1 + 756*q^2 + 4032*q^3 + 20412*q^4 + ... = (1-q^2)^(-756) * (1-q^3)^(-4032) * (1-q^4)^265734 * ... .
		

Crossrefs

A004046 Theta series of extremal 3-modular even 24-dimensional lattice with minimal norm 6 and det = 3^12.

Original entry on oeis.org

1, 0, 0, 26208, 530712, 6368544, 47331648, 256864608, 1116087336, 4092877152, 12996075456, 37058557536, 96952754808, 232778774592, 526258264896, 1128148021728, 2286143305992, 4451523096384, 8386247967552, 15130902687264, 26614339616592, 45684687301344
Offset: 0

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Author

Keywords

Comments

Cubic AGM theta functions: a(q) (see A004016), b(q) (A005928), c(q) (A005882).
G.f. is a period 1 Fourier series which satisfies f(-1 / (3 t)) = 729 (t/i)^12 f(t) where q = exp(2 Pi i t). - Michael Somos, Dec 21 2015

Examples

			G.f. = 1 + 26208*x^3 + 530712*x^4 + 6368544*x^5 + 47331648*x^6 + ...
G.f. = 1 + 26208*q^6 + 530712*q^8 + 6368544*q^10 + 47331648*q^12 + ...
		

References

  • N. J. A. Sloane, Seven Staggering Sequences, in Homage to a Pied Puzzler, E. Pegg Jr., A. H. Schoen and T. Rodgers (editors), A. K. Peters, Wellesley, MA, 2009, pp. 93-110.

Crossrefs

Cf. A107657.

Programs

  • Magma
    A := Basis( ModularForms( Gamma1(3), 12), 22);  A[1] + 26208*A[4] + 530712*A[5]; /* Michael Somos, Dec 21 2015 */
    
  • Mathematica
    a[ n_] := With[ {U1 = QPochhammer[ q]^3, U3 = QPochhammer[ q^3]^3, U9 = QPochhammer[ q^9]^3}, With[ {z = ( 1 + 9 q U9/U1)^3}, SeriesCoefficient[ (U1^3/U3)^4 (27 z^4 - 72 z^3 + 64 z^2 + 16 z - 8) / 27, {q, 0, n}]]]; (* Michael Somos, Dec 25 2015 *)
  • PARI
    th3 = sum(n=1,noo\2, 2*x^(4*n^2), 1+A);
    th4 = sum(n=1,noo\2, (-1)^n*2*x^(4*n^2), 1+A);
    th2 = sum(n=0,noo\2, 2*x^(4*n^2+4*n+1), A);
    chk("th3^4 == th4^4+th2^4");
    /* A004016(x^4) */
    phi0 = th2*subst(th2,x,x^3)+ th3*subst(th3,x,x^3);
    /* 2*x*A033762(x^2) */
    phi1 = th2*subst(th3,x,x^3)+ th3*subst(th2,x,x^3);
    /* A004010(x^2) */
    K_12 = phi0^6+45*phi0^2*phi1^4+18*phi1^6;
    a=phi0;b=phi1;
    A004046=a^12-9/2*a^8*b^4+414*a^6*b^6+1458*a^4*b^8+1998*a^2*b^10+459/2*b^12;
    
  • PARI
    {a(n) = my(A, U1, U3, U9, z); if( n<0, 0, A = x * O(x^n); U1 = eta(x + A)^3; U3 = eta(x^3 + A)^3; U9 = eta(x^9 + A)^3; z = (1 + 9 * x * U9/U1)^3; polcoeff( (U1^3/U3)^4 * (27*z^4 - 72*z^3 + 64*z^2 + 16*z - 8) / 27, n))}; /* Michael Somos, Dec 25 2015 */

Formula

Theta series = a^12 - 9/2*a^8*b^4 + 414*a^6*b^6 + 1458*a^4*b^8 + 1998*a^2*b^10 + 459/2*b^12 (see PARI code for details).
G.f.: (27*a(x)^12 - 72*a(x)^9*b(x)^3 + 64*a(x)^6*b(x)^6 + 16*a(x)^3*b(x)^9 - 8*b(x)^12) / 27 where a(), b() are cubic AGM theta functions, - Michael Somos, Dec 25 2015

Extensions

PARI code from Michael Somos, Jun 07 2005

A015235 Theta series of lattice Kappa_8.

Original entry on oeis.org

1, 0, 132, 192, 828, 1152, 2796, 2880, 6828, 5376, 14904, 10944, 20772, 18432, 40224, 25920, 53964, 41472, 76452, 58176, 107784, 69504, 156816, 101376, 163284, 131328, 259032, 147072, 295200, 206208, 357480, 250560, 432780, 269568, 576072, 365184, 555804, 426240
Offset: 0

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Author

Keywords

Examples

			G.f. = 1 + 132*q^4 + 192*q^6 + ...
		

References

  • J. H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 161.

Crossrefs

Cf. A015236 (K_7), A015233 (K_9), A015232 (K_10), A015229 (K_11), A004010 (K_12), A029897 (K_13), A047628 (K_14).

Programs

  • Sage
    L = [1, 0, 132, 192, 828, 1152, 2796, 2880, 6828, 5376]
    M = ModularForms(Gamma0(12),4)
    bases = [.q_expansion(35) for  in M.integral_basis()]
    f = sum(x*y for (x,y) in zip(bases,L)); list(f) # Andy Huchala, Jul 23 2021

Extensions

More terms from Sean A. Irvine, Feb 26 2020

A320676 Expansion of (r(q) * s(q))^3 where r(), s() are cubic AGM theta functions.

Original entry on oeis.org

1, 9, -27, -261, 765, 2214, -11529, 11304, 24813, -81423, 71118, 106812, -354609, 262350, 385992, -1049166, 739917, 990306, -2713203, 1709604, 2287710, -5646600, 3707532, 4448952, -11344833, 6737319, 8450838, -19943757, 12298248, 14238558, -34639974, 19856736
Offset: 0

Views

Author

Seiichi Manyama, Oct 19 2018

Keywords

Comments

Cubic AGM theta functions: r(q) (see A004016), s(q) (A005928), t(q) (A005882).

Crossrefs

Formula

Expansion of (eta(q)^3 * (eta(q)^3 + 9 * eta(q^9)^3) / eta(q^3)^2)^3 in powers of q.

A320677 Expansion of s(q)^6 where s() is cubic AGM theta functions.

Original entry on oeis.org

1, -18, 135, -504, 657, 2052, -10071, 12384, 20277, -83610, 72090, 122040, -355581, 245124, 379512, -1050624, 770589, 966492, -2700081, 1724616, 2287062, -5636880, 3616164, 4471632, -11385657, 6820722, 8554194, -19963440, 12302568, 14113332, -34631226, 19737936
Offset: 0

Views

Author

Seiichi Manyama, Oct 19 2018

Keywords

Comments

Cubic AGM theta functions: r(q) (see A004016), s(q) (A005928), t(q) (A005882).

Crossrefs

s(q)^m: A005928 (m=1), A242874 (m=2), A109041 (m=3), A133078 (m=4), this sequence (m=6).

Formula

Expansion of (eta(q)^3/eta(q^3))^6 in powers of q.
Showing 1-6 of 6 results.