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 1-7 of 7 results.

A002288 G.f.: q * Product_{m>=1} (1-q^m)^8*(1-q^2m)^8.

Original entry on oeis.org

0, 1, -8, 12, 64, -210, -96, 1016, -512, -2043, 1680, 1092, 768, 1382, -8128, -2520, 4096, 14706, 16344, -39940, -13440, 12192, -8736, 68712, -6144, -34025, -11056, -50760, 65024, -102570, 20160, 227552, -32768, 13104, -117648, -213360, -130752, 160526, 319520
Offset: 0

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Author

Keywords

Comments

This is Glaisher's Theta(n). - N. J. A. Sloane, Nov 26 2018
Number 2 of the 74 eta-quotients listed in Table I of Martin (1996).
Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = q - 8*q^2 + 12*q^3 + 64*q^4 - 210*q^5 - 96*q^6 + 1016*q^7 - 512*q^8 + ...
		

References

  • J. W. L. Glaisher, On the representation of a number as a sum of 14 and 16 squares, Quart. J. Math. 38 (1907), 178-236 (see p. 198).
  • F. Hirzebruch et al., Manifolds and Modular Forms, Vieweg 1994 p 133.
  • G. Shimura, Modular forms of half-integral weight, pp. 57-74 of Modular Functions of One Variable I (Antwerp 1972), Lect. Notes Math. 320 (1973).
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A030211.

Programs

  • Magma
    Basis( CuspForms( Gamma0(2), 8), 100) [1]; /* Michael Somos, Dec 09 2013 */
  • Maple
    t1 := product((1-q^m)^8,m=1..40): subs(q=q^2,t1): series(q*t1*%,q,40);
  • Mathematica
    max = 36; f[q_] := q*Product[(1-q^m)^8*(1-q^(2m))^8, {m, 1, max}]; CoefficientList[ Series[f[q], {q, 0, max}], q] (* Jean-François Alcover, Jul 18 2012 *)
    a[ n_] := SeriesCoefficient[ q (QPochhammer[ q] QPochhammer[ q^2])^8, {q, 0, n}]; (* Michael Somos, Apr 09 2013 *)
    a[ n_] := SeriesCoefficient[(EllipticTheta[ 4, 0, q] EllipticTheta[ 2, 0, q^(1/2)] / 2)^8, {q, 0, n}]; (* Michael Somos, Dec 09 2013 *)
  • PARI
    {a(n) = local(A); if( n<1, 0, n--; A = x * O(x^n); polcoeff( (eta(x + A) * eta(x^2 + A))^8, n))}; /* Michael Somos, Jul 16 2004 */
    
  • PARI
    q='q+O('q^50); concat(0, Vec((eta(q)*eta(q^2))^8)) \\ Altug Alkan, Sep 19 2018
    
  • Sage
    CuspForms( Gamma0(2), 8, prec=100).0; # Michael Somos, May 28 2013
    

Formula

Expansion of cusp form (e(1)-e(2))(e(1)-e(3))(e(2)-e(3))^2 for GAMMA_0(2).
Expansion of q * psi(q)^8 * phi(-q)^8 in powers of q where psi(), phi() are Ramanujan theta functions. - Michael Somos, Dec 09 2013
Expansion of (eta(q) * eta(q^2))^8 in powers of q. - Michael Somos, Mar 18 2003
Euler transform of period 2 sequence [ -8, -16, ... ].
a(n) is multiplicative with a(2^e) = (-8)^e, a(p^e) = a(p) * a(p^(e-1)) - p^7 * a(p^(e-2)). - Michael Somos, Mar 08 2006
Given A = A0 + A1 + A2 + A3 is the 4-section, then 0 = A2^3 + 2 * A0 * (A1^2 + A3^2) - 4 * A1*A2*A3 - 3 * A0^2*A2. - Michael Somos, Mar 08 2006
G.f. is a period 1 Fourier series which satisfies f(-1 / (2 t)) = 16 (t/i)^8 f(t) where q = exp(2 Pi i t). - Michael Somos, Apr 09 2013
a(2*n) = -8 * a(n). Convolution square of A030211. - Michael Somos, Apr 09 2013
G.f.: x*exp(8*Sum_{k>=1} (sigma(2*k) - 4*sigma(k))*x^k/k). - Ilya Gutkovskiy, Sep 19 2018

Extensions

Extended, and better description added by N. J. A. Sloane, Jan 15 1996

A134461 Expansion of (phi(x) * psi(-x))^4 in powers of x where phi(), psi() are Ramanujan theta functions.

Original entry on oeis.org

1, 4, -2, -24, -11, 44, 22, -8, 50, -44, -96, 56, -121, -152, 198, 160, 176, 48, -162, 88, -198, -52, 22, -528, 233, 200, -242, -88, -176, 668, 550, 264, -44, -188, 224, -728, 154, -484, -1056, 656, -311, -236, -100, 792, 714, -528, 640, 88, -478, -484, 1566, 968, 192, 780, -1994, -648, -942
Offset: 0

Views

Author

Michael Somos, Oct 26 2007

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).
Number 34 of the 74 eta-quotients listed in Table I of Martin (1996).

Examples

			G.f. = 1 + 4*x - 2*x^2 - 24*x^3 - 11*x^4 + 44*x^5 + 22*x^6 - 8*x^7 + ...
G.f. = q + 4*q^3 - 2*q^5 - 24*q^7 - 11*q^9 + 44*q^11 + 22*q^13 - 8*q^15 + ...
		

Crossrefs

Cf. A216711.
The same as A030211 except for signs.

Programs

  • Magma
    A := Basis( CuspForms( Gamma0(16), 4), 115); A[1] + 4*A[3]; /* Michael Somos, Jun 10 2015 */
  • Mathematica
    a[ n_] := SeriesCoefficient[ (EllipticTheta[ 4, 0, x^2] EllipticTheta[ 2, 0, x^(1/2)] / (2 x^(1/8)))^4, {x, 0, n}]; (* Michael Somos, Jun 10 2015 *)
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( ( eta(x^2 + A)^4 / (eta(x + A) * eta(x^4 + A)) )^4, n))};
    

Formula

Expansion of q^(-1/2) * (eta(q^2)^4 / (eta(q) * eta(q^4)))^4 in powers of q.
Euler transform of period 4 sequence [ 4, -12, 4, -8, ...].
a(n) = b(2*n + 1) where b() is multiplicative with b(2^e) = 0^e, b(p^e) = b(p)*b(p^(e-1)) - p^3*b(p^(e-2)).
G.f. is a period 1 Fourier series which satisfies f(-1 / (16 t)) = 256 (t/i)^4 f(t) where q = exp(2 Pi i t).
G.f.: (Product_{k>0} (1 + x^k) * (1 - x^(2*k))^2 / (1 + x^(2*k)))^4.
a(n) = (-1)^n * A030211(n).
Convolution square is A216711. - Michael Somos, Jun 10 2015

A259491 Expansion of (eta(q)^2 * eta(q^2) * eta(q^4)^3 / eta(q^8)^2)^2 in powers of q.

Original entry on oeis.org

1, -4, 0, 16, -16, 8, 0, -96, 112, 44, 0, 176, -448, -88, 0, -32, 1136, -200, 0, -176, -2016, 384, 0, 224, 3136, 484, 0, -608, -5504, -792, 0, 640, 9328, -704, 0, 192, -12112, 648, 0, 352, 14112, 792, 0, -208, -21312, -88, 0, -2112, 31808, -932, 0, 800
Offset: 0

Views

Author

Michael Somos, Jun 28 2015

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).

Examples

			G.f. = 1 - 4*q + 16*q^3 - 16*q^4 + 8*q^5 - 96*q^7 + 112*q^8 + 44*q^9 + ...
		

Crossrefs

Programs

  • Magma
    A := Basis( ModularForms( Gamma1(8), 4), 52); A[1] - 4*A[2] + 16*A[4] - 16*A[5] + 8*A[6] - 96*A[8] + 112*A[9];
  • Mathematica
    a[ n_] := SeriesCoefficient[ (QPochhammer[ q]^2 QPochhammer[ q^2] QPochhammer[ q^4]^3 / QPochhammer[ q^8]^2)^2, {q, 0, n}];
    a[ n_] := SeriesCoefficient[ (EllipticTheta[ 3, 0, q] EllipticTheta[ 3, 0, q^2] EllipticTheta[ 4, 0, q]^2)^2, {q, 0, n}];
    a[ n_] := SeriesCoefficient[ (EllipticTheta[ 4, 0, q] EllipticTheta[ 4, 0, q^2] EllipticTheta[ 4, 0, q^4]^2)^2, {q, 0, n}];
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( (eta(x + A)^2 * eta(x^2 + A) * eta(x^4 + A)^3 / eta(x^8 + A)^2)^2, n))};
    

Formula

Expansion of (phi(q) * phi(q^2) * phi(-q)^2)^2 in powers of q where phi() is a Ramanujan theta function.
Euler transform of period 8 sequence [ -4, -6, -4, -12, -4, -6, -4, -8, ...].
G.f.: Product_{k>0} ((1 - x^k)^4 * (1 + x^k)^2 * (1 + x^(2*k)) / (1 + x^(4*k))^2)^2.
a(2*n + 1) = -4 * A030211(n). a(4*n) = A035016(n). a(4*n + 2) = 0.
Convolution square of A131999.

A289277 a(n) = A005259(n) mod 2*n+1.

Original entry on oeis.org

0, 2, 3, 3, 7, 0, 9, 5, 16, 6, 1, 13, 4, 26, 24, 26, 22, 30, 23, 32, 7, 9, 43, 11, 37, 29, 23, 0, 49, 40, 1, 44, 20, 54, 19, 18, 8, 20, 22, 55, 4, 70, 80, 62, 2, 31, 37, 20, 7, 44, 51, 62, 64, 76, 77, 41, 75, 75, 115, 68, 0, 35, 42, 11, 88, 59, 101, 35, 119, 11
Offset: 0

Views

Author

Seiichi Manyama, Jul 01 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Mod[Sum[(Binomial[n, k] Binomial[n + k, k])^2, {k, 0, n}], 2n + 1], {n, 0, 100}] (* Indranil Ghosh, Jul 01 2017 *)
  • PARI
    a(n) = sum(k=0, n, (binomial(n, k)*binomial(n+k, k))^2) % (2*n+1); \\ Michel Marcus, Jul 01 2017

Formula

If m = 2*n + 1 is a prime, a(n) = A030211(n) mod m.

A289278 a(n) = A005259(n) mod (2*n+1)^2.

Original entry on oeis.org

0, 5, 23, 24, 34, 77, 22, 140, 50, 44, 169, 473, 354, 539, 198, 801, 385, 135, 1207, 617, 1483, 52, 2023, 528, 723, 2273, 2567, 1265, 1303, 2813, 550, 233, 1775, 188, 2365, 728, 154, 1520, 4180, 5585, 571, 236, 3650, 2672, 714, 4581, 4966, 2490, 8931, 4796, 1566
Offset: 0

Views

Author

Seiichi Manyama, Jul 01 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Mod[Sum[(Binomial[n, k] Binomial[n + k, k])^2, {k, 0, n}], (2n + 1)^2], {n, 0, 100}] (* Indranil Ghosh, Jul 01 2017 *)
  • PARI
    a(n) = sum(k=0, n, (binomial(n, k)*binomial(n+k, k))^2) % (2*n+1)^2; \\ Michel Marcus, Jul 01 2017

Formula

If m = 2*n + 1 is a prime, a(n) = A030211(n) mod m^2.

A291124 Expansion of phi(x)^6 * phi(-x)^2 in powers of x where phi() is a Ramanujan theta function.

Original entry on oeis.org

1, 8, 16, -32, -144, -16, 448, 192, -912, -88, 2016, -352, -4032, 176, 5504, 64, -7056, 400, 12112, 352, -18144, -768, 21312, -448, -25536, -968, 35168, 1216, -49536, 1584, 56448, -1280, -56208, 1408, 78624, -384, -109008, -1296, 109760, -704, -114912, -1584
Offset: 0

Views

Author

Michael Somos, Aug 17 2017

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700)

Examples

			G.f. = 1 + 8*x + 16*x^2 - 32*x^3 - 144*x^4 - 16*x^5 + 448*x^6 + 192*x^7 + ...
		

Crossrefs

Programs

  • Magma
    A := Basis( ModularForms( Gamma0(16), 4), 42); A[1] + 8*A[2] + 16*A[3] - 32*A[4] - 144*A[5] - 16*A[6] + 448*A[7] + 192*A[8] - 912*A[9];
  • Mathematica
    a[ n_] := SeriesCoefficient[ EllipticTheta[ 3, 0, x]^6 EllipticTheta[ 4, 0, x]^2, {x, 0, n}];
    a[ n_] := SeriesCoefficient[ (QPochhammer[x^2]^7 / (QPochhammer[ x]^2 QPochhammer[ x^4]^3))^4, {x, 0, n}];
  • PARI
    {a(n) = my(A); if( n<0, 0, A = x * O(x^n); polcoeff( (eta(x^2 + A)^7 / (eta(x + A)^2 * eta(x^4 + A)^3))^4, n))};
    
  • PARI
    lista(nn) = {q='q+O('q^nn); Vec((eta(q^2)^7/(eta(q)^2*eta(q^4)^3))^4)} \\ Altug Alkan, Mar 21 2018
    

Formula

Expansion of (eta(q^2)^7 / (eta(q)^2 * eta(q^4)^3))^4 in powers of q.
Euler transform of period 4 sequence [8, -20, 8, -8, ...].
G.f. is a period 1 Fourier series which satisfies f(-1 / (8 t)) = 512 (t/i)^4 g(t) where q = exp(2 Pi i t) and g(t) is the g.f. for A045820.
G.f.: Product_{k>0} (1 - x^(2*k))^28 / ((1 - x^k)^8 * (1 - x^(4*k))^12).
a(2*n + 1) = 8 * A030211(n). a(4*n + 2) = 16 * A045823(n).
a(2*n) = 16 * (-1)^n * (-sigma_3(n) + sigma_3(n/4)) where sigma_3(n) is the sum of the cubes of the divisors of n if n is an integer else 0.
Convolution square of A207541.

A319456 a(n) = [x^n] Product_{k>=1} ((1 - x^k)*(1 - x^(2*k)))^n.

Original entry on oeis.org

1, -1, -3, 14, -11, -81, 282, -57, -2043, 5405, 2417, -46476, 94522, 110512, -943407, 1505289, 2807589, -16888311, 23645199, 46006542, -265972791, 472882620, 187884672, -3981273597, 14234579226, -19187383356, -78662039004, 502118911904, -847583768679, -2627514175002
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 19 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[Product[((1 - x^k) (1 - x^(2 k)))^n , {k, 1, n}], {x, 0, n}], {n, 0, 29}]
    Table[SeriesCoefficient[(QPochhammer[x] QPochhammer[x^2])^n, {x, 0, n}], {n, 0, 29}]
    Table[SeriesCoefficient[Exp[n Sum[(DivisorSigma[1, 2 k] - 4 DivisorSigma[1, k]) x^k/k, {k, 1, n}]], {x, 0, n}], {n, 0, 29}]

Formula

a(n) = [x^n] Product_{k>=1} (1 - x^(2*k))^(2*n)/(1 + x^k)^n.
a(n) = [x^n] exp(n*Sum_{k>=1} (sigma(2*k) - 4*sigma(k))*x^k/k).
Showing 1-7 of 7 results.