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 1-2 of 2 results.

A007653 Coefficients of L-series for elliptic curve "37a1": y^2 + y = x^3 - x.

Original entry on oeis.org

1, -2, -3, 2, -2, 6, -1, 0, 6, 4, -5, -6, -2, 2, 6, -4, 0, -12, 0, -4, 3, 10, 2, 0, -1, 4, -9, -2, 6, -12, -4, 8, 15, 0, 2, 12, -1, 0, 6, 0, -9, -6, 2, -10, -12, -4, -9, 12, -6, 2, 0, -4, 1, 18, 10, 0, 0, -12, 8, 12, -8, 8, -6, -8, 4, -30, 8, 0, -6, -4, 9, 0, -1, 2, 3, 0, 5, -12, 4, 8, 9, 18, -15, 6, 0, -4, -18, 0, 4, 24, 2, 4, 12, 18, 0
Offset: 1

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Author

Keywords

Comments

G.f. is Fourier series of a weight 2 level 37 modular cusp form.

Examples

			G.f. = q - 2*q^2 - 3*q^3 + 2*q^4 - 2*q^5 + 6*q^6 - q^7 + 6*q^9 + 4*q^10 - 5*q^11 + ...
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Magma
    A := Basis( CuspForms( Gamma0(37), 2), 72); A[1] - 2*A[2]; /* Michael Somos, Jan 02 2017 */
    
  • PARI
    {a(n) = if( n<1, 0, ellak( ellinit([ 0, 0, -1, -1, 0]), n))}; /* Michael Somos, Mar 04 2011 */
    
  • PARI
    {a(n) = if( n<1, 0, qfrep([ 2, 1, 0, 1; 1, 8, 1, -3; 0, 1, 10, 2; 1, -3, 2, 12 ], n, 1)[n] - qfrep([ 4, 1, 2, 1; 1, 4, 1, 0; 2, 1, 6, -2; 1, 0, -2, 20 ], n, 1)[n])}; /* Michael Somos, Apr 02 2006 */
    
  • Sage
    def a(n):
        return EllipticCurve("37a1").an(n)  # Robin Visser, Aug 02 2023

Formula

a(3^n) = A000748(n).
a(n) = (A045866(n) - A045867(n)) / 2.
a(n) is multiplicative with a(p^e) = a(p) * a(p^(e-1)) - p * a(p^(e-2)) where a(p) = p+1 - number of solutions of y^2 + y = x^3 - x modulo p including the point at infinity. - Michael Somos, Mar 03 2011
G.f. is a period 1 Fourier series which satisfies f(-1 / (37 t)) = -37 (t/i)^2 f(t) where q = exp(2 Pi i t).

Extensions

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jun 22 2000

A045866 Theta series of quadratic form with Gram matrix [ 2, 1, 0, 1; 1, 8, 1, -3; 0, 1, 10, 2; 1, -3, 2, 12 ].

Original entry on oeis.org

1, 2, 0, 0, 6, 2, 14, 4, 10, 14, 16, 4, 12, 6, 18, 22, 18, 14, 14, 14, 24, 24, 34, 20, 40, 18, 32, 16, 36, 24, 36, 16, 50, 48, 36, 34, 74, 0, 40, 42, 60, 16, 58, 34, 44, 40, 44, 24, 96, 30, 64, 50, 64, 36, 98, 58, 80, 54, 48, 52, 124, 36, 72, 64, 74, 60, 66, 52, 80, 60, 92, 52
Offset: 0

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Author

Keywords

Comments

This is the 4-dimensional Elkies_B lattice.

Examples

			1 + 2*q^2 + 6*q^8 + 2*q^10 + 14*q^12 + 4*q^14 + 10*q^16 + 14*q^18 + 16*q^20 + ...
		

Crossrefs

Dual lattice to that in A045867.

Programs

  • PARI
    B(x, y, z, w)=2*x^2+8*y^2+10*z^2+12*w^2+2*x*(y+w)+2*y*(z-3*w)+4*z*w;
    thetaB(n, N, bx, by, bz, bw, ix, iy, iz, iw, nn)=n=2*n; bx=floor(sqrt(n)*(1+1/sqrt(6))); bz=floor(sqrt(n/7)); bw=floor(sqrt(n/6)); by=floor(sqrt(n/3)); N=vector(n/2+2); for(ix=-bx, bx, for(iy=-by, by, for(iz=-bz, bz, for(iw=-bw, bw, nn=B(ix, iy, iz, iw); if (nn<=n, N[1+nn/2]++); )))); N;
    thetaB(80)
    
  • PARI
    {a(n)=if(n<1, n==0, qfrep([ 2, 1, 0, 1; 1, 8, 1, -3; 0, 1, 10, 2; 1, -3, 2, 12 ], n, 1)[n]*2)} /* Michael Somos, Apr 02 2006 */

Extensions

More terms from Kok Seng Chua (chuaks(AT)ihpc.nus.edu.sg), Jun 22 2000
Showing 1-2 of 2 results.