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 1-9 of 9 results.

A259150 Decimal expansion of phi(exp(-4*Pi)), where phi(q) = Product_{n>=1} (1-q^n) is the Euler modular function.

Original entry on oeis.org

9, 9, 9, 9, 9, 6, 5, 1, 2, 6, 4, 5, 4, 8, 2, 2, 3, 4, 2, 9, 5, 0, 9, 8, 9, 1, 6, 8, 5, 2, 1, 1, 9, 2, 4, 7, 6, 5, 7, 5, 0, 9, 7, 8, 9, 3, 2, 6, 3, 4, 5, 8, 4, 8, 4, 4, 7, 7, 3, 2, 6, 9, 1, 0, 0, 4, 7, 2, 0, 1, 5, 2, 5, 7, 6, 7, 4, 4, 8, 2, 0, 3, 2, 6, 8, 9, 6, 2, 4, 9, 7, 3, 0, 1, 1, 9, 7, 2, 8, 1, 0, 8, 9
Offset: 0

Views

Author

Jean-François Alcover, Jun 19 2015

Keywords

Examples

			0.99999651264548223429509891685211924765750978932634584844773269100472...
		

Crossrefs

Cf. A048651 phi(1/2), A100220 phi(1/3), A100221 phi(1/4), A100222 phi(1/5), A132034 phi(1/6), A132035 phi(1/7), A132036 phi(1/8), A132037 phi(1/9), A132038 phi(1/10), A292862 phi(exp(-Pi/8)), A292863 phi(exp(-Pi/4)), A259147 phi(exp(-Pi/2)), A259148 phi(exp(-Pi)), A259149 phi(exp(-2*Pi)), A292888 phi(exp(-3*Pi)), A292905 phi(exp(-5*Pi)), A363018 phi(exp(-6*Pi)), A363117 phi(exp(-7*Pi)), A259151 phi(exp(-8*Pi)), A363118 phi(exp(-9*Pi)), A363019 phi(exp(-10*Pi)), A363081 phi(exp(-11*Pi)), A363020 phi(exp(-12*Pi)), A363178 phi(exp(-13*Pi)), A363119 phi(exp(-14*Pi)), A363179 phi(exp(-15*Pi)), A292864 phi(exp(-16*Pi)), A363120 phi(exp(-18*Pi)), A363021 phi(exp(-20*Pi)).

Programs

  • Mathematica
    phi[q_] := QPochhammer[q, q]; RealDigits[phi[Exp[-4*Pi]], 10, 103] // First

Formula

phi(q) = QPochhammer(q,q) = (q;q)_infinity.
phi(q) also equals theta'(1, 0, sqrt(q))^(1/3)/(2^(1/3)*q^(1/24)), where theta' is the derivative of the elliptic theta function theta(a,u,q) w.r.t. u.
phi(exp(-4*Pi)) = exp(Pi/6)*Gamma(1/4)/(2^(11/8)*Pi^(3/4)).
A259150 = A259148 * exp(Pi/8)/sqrt(2). - Vaclav Kotesovec, Jul 03 2017

A292820 Decimal expansion of Product_{k>=1} (1 + exp(-Pi*k)).

Original entry on oeis.org

1, 0, 4, 5, 2, 5, 0, 2, 1, 4, 3, 5, 4, 7, 1, 1, 9, 4, 2, 5, 4, 7, 5, 9, 5, 0, 1, 2, 2, 0, 3, 5, 6, 2, 0, 6, 8, 0, 0, 3, 4, 2, 4, 7, 8, 2, 1, 5, 5, 5, 8, 6, 9, 1, 5, 5, 0, 0, 5, 2, 0, 9, 8, 5, 2, 5, 7, 1, 1, 7, 5, 7, 9, 3, 9, 6, 9, 6, 0, 3, 2, 7, 9, 0, 4, 0, 8, 1, 7, 0, 5, 6, 2, 0, 9, 7, 6, 8, 2, 9, 3, 9, 0, 9, 6
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 24 2017

Keywords

Examples

			1.045250214354711942547595012203562068003424782155586915500520985257117...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[E^(Pi/24) / 2^(1/8), 10, 120][[1]]
    RealDigits[QPochhammer[-1, E^(-Pi)]/2, 10, 120][[1]]
  • PARI
    exp(Pi/24)/sqrtn(2,8) \\ Charles R Greathouse IV, Mar 13 2018

Formula

Equals exp(Pi/24) / 2^(1/8).
Equals A259149 / A259148.

A292821 Decimal expansion of Product_{k>=1} (1 + exp(-2*Pi*k)).

Original entry on oeis.org

1, 0, 0, 1, 8, 7, 0, 9, 4, 3, 1, 2, 3, 2, 7, 9, 8, 8, 6, 4, 6, 3, 5, 3, 4, 0, 8, 7, 9, 6, 7, 4, 1, 5, 2, 1, 8, 0, 8, 3, 1, 9, 9, 7, 1, 9, 5, 0, 2, 6, 3, 1, 2, 5, 9, 1, 9, 4, 9, 8, 6, 3, 9, 1, 2, 9, 7, 5, 2, 1, 4, 0, 0, 9, 4, 4, 5, 5, 4, 6, 5, 7, 3, 8, 5, 3, 7, 9, 0, 4, 6, 9, 8, 4, 3, 9, 9, 0, 2, 9, 4, 0, 2, 6, 7
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 24 2017

Keywords

Examples

			1.001870943123279886463534087967415218083199719502631259194986391297521...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[E^(Pi/12) / 2^(3/8), 10, 120][[1]]
    RealDigits[QPochhammer[-1, E^(-2*Pi)]/2, 10, 120][[1]]
  • PARI
    exp(Pi/12)/sqrtn(8,8) \\ Charles R Greathouse IV, Mar 13 2018

Formula

Equals exp(Pi/12) / 2^(3/8).
Equals A259150 / A259149.

A292819 Decimal expansion of Product_{k>=1} (1 + exp(-Pi*k/2)).

Original entry on oeis.org

1, 2, 7, 4, 3, 9, 4, 9, 8, 5, 6, 3, 5, 7, 9, 9, 3, 0, 7, 2, 0, 3, 5, 3, 3, 9, 7, 1, 9, 2, 2, 3, 0, 3, 7, 5, 6, 1, 9, 3, 5, 6, 2, 5, 0, 7, 8, 6, 6, 3, 7, 0, 8, 6, 7, 4, 2, 7, 4, 0, 0, 2, 0, 2, 0, 6, 4, 2, 2, 0, 8, 4, 5, 5, 9, 8, 3, 9, 7, 4, 3, 7, 9, 4, 1, 6, 2, 4, 3, 8, 3, 7, 4, 8, 3, 4, 3, 5, 4, 0, 7, 3, 3, 9, 1
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 24 2017

Keywords

Examples

			1.274394985635799307203533971922303756193562507866370867427400202064220...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[E^(Pi/48) / (2^(1/16) * (Sqrt[2]-1)^(1/4)), 10, 120][[1]]
    RealDigits[QPochhammer[-1, E^(-Pi/2)]/2, 10, 120][[1]]

Formula

Equals exp(Pi/48) / (2^(1/16) * (sqrt(2)-1)^(1/4)).
Equals A259148 / A259147.

A014103 Expansion of (eta(q^2) / eta(q))^24 in powers of q.

Original entry on oeis.org

1, 24, 300, 2624, 18126, 105504, 538296, 2471424, 10400997, 40674128, 149343012, 519045888, 1718732998, 5451292992, 16633756008, 49010118656, 139877936370, 387749049720, 1046413709980, 2754808758144, 7087483527072, 17848133716832, 44056043512488, 106727749011456
Offset: 1

Views

Author

Keywords

Comments

Ramanujan theta functions: f(q) (see A121373), phi(q) (A000122), psi(q) (A010054), chi(q) (A000700).
Given g.f. A(q), Greenhill (1895) denotes -64 * A(q^2) by tau_0 on page 409 equation (43). - Michael Somos, Jul 17 2013

Examples

			G.f. = q + 24*q^2 + 300*q^3 + 2624*q^4 + 18126*q^5 + 105504*q^6 + 538296*q^7 + ...
		

References

  • John H. Conway and N. J. A. Sloane, "Sphere Packings, Lattices and Groups", Springer-Verlag, p. 102.
  • Albert Eagle, Elliptic functions as they should be, Galloway and Porter Ltd., Cambridge, pp. 72-73.

Crossrefs

Programs

  • Maple
    q*mul((1+q^m)^24,m=1..30); seq(coeff(series(%,q,n+1),q,n), n=1..25);
  • Mathematica
    a[ n_] := SeriesCoefficient[ q QPochhammer[ q, q^2]^-24, {q, 0, n}]; (* Michael Somos, Jul 11 2011 *)
    a[ n_] := SeriesCoefficient[ q / Product[ 1 - q^k, {k, 1, n + 1, 2}]^24, {q, 0, n}]; (* Michael Somos, Jul 11 2011 *)
    a[ n_] := With[ {m = ModularLambda[ Log[q]/(Pi I)]}, SeriesCoefficient[ (m/16)^2 / (1 - m), {q, 0, 2 n}]]; (* Michael Somos, Jul 11 2011 *)
    a[ n_] := With[ {m = InverseEllipticNomeQ @ q}, SeriesCoefficient[ (m/16)^2 /(1 - m), {q, 0, 2 n}]]; (* Michael Somos, Jul 11 2011 *)
    eta[q_]:=q^(1/6) QPochhammer[q]; a[n_]:=SeriesCoefficient[(eta[q^2] / eta[q])^24, {q, 0, n}]; Table[a[n], {n, 4, 25}] (* Vincenzo Librandi, Oct 18 2018 *)
  • PARI
    {a(n) = polcoeff( x * prod( k=1, n, 1 + x^k, 1 + x * O(x^n))^24, n)};
    
  • PARI
    {a(n) = my(A, A2, m); if( n<0, 0, A = x + O(x^2); m=1; while( m<=n, m*=2; A = subst( A, x, x^2); A2 = A * (1 + 16*A); A = 8 * A2 + (1 + 32*A) * sqrt(A2)); polcoeff( A + 16 * A^2, n))};
    
  • PARI
    {a(n) = my(A); if( n<1, 0, n--; A = x * O(x^n); polcoeff( (eta(x^2 + A) / eta(x + A))^24, n))};

Formula

REVERT(A005149).
Euler transform of period 2 sequence [ 24, 0, 24, 0, ... ]. - Michael Somos, Mar 19 2004
Expansion of (lambda(q) / 16)^2 / (1 - lambda(q)) in powers of q = exp(2 Pi i t) where lambda() is the elliptic modular function A115977. - Michael Somos, Nov 19 2005
Expansion of q / chi(-q)^24 in powers of q where chi() is a Ramanujan theta function.
Expansion of (theta_2(q) * theta_3(q) / (2 * theta_4(q)^2))^4 = (theta_2(q^(1/2))^2 / (4*theta_4(q^(1/2)) * theta_3(q^(1/2))))^4 in powers of q.
G.f.: x * Product_{k > 0} (1 + x^k)^24 = x / Product_{k > 0} (1 - x^(2*k - 1))^24.
G.f. A(x) satisfies 0 = f(A(x), A(x^2)) where f(u, v) = u^2 - v - 48*u*v - 4096*u*v^2. - Michael Somos, Mar 19 2004
G.f. is a period 1 Fourier series which satisfies f(-1 / (2 t)) = (1/4096) g(t) where q = exp(2 Pi i t) and g() is the g.f. of A007191. - Michael Somos, Aug 19 2007
j(q) = (f(q) + 16)^3 / f(q), j(q^2) = (f(q) + 256)^3 / f(q)^2 where j(q) is the g.f. for A000521 and f(q) is 4096 times the g.f. for a(n). - Michael Somos, Oct 01 2007
Convolution inverse of A007191. Series reversion of A005149.
Sum_{n>=1} exp(-2*Pi*n)*a(n) = 1/512. - Simon Plouffe, Feb 20 2011 [Proof: Sum_{n>=0} a(n)/exp(2*Pi*n) = exp(-2*Pi) * (phi(exp(-4*Pi)) / phi(exp(-2*Pi)))^24 = exp(-2*Pi) * A292821^24, where phi(q) is the Euler modular function. - Vaclav Kotesovec, May 13 2023]
a(n) ~ exp(2 * Pi * sqrt(2*n)) / (4096 * 2^(3/4) * n^(3/4)). - Vaclav Kotesovec, Mar 05 2015
a(1) = 1, a(n) = (24/(n-1))*Sum_{k=1..n-1} A000593(k)*a(n-k) for n > 1. - Seiichi Manyama, Apr 01 2017
G.f.: x*exp(24*Sum_{k>=1} (-1)^(k+1)*x^k/(k*(1 - x^k))). - Ilya Gutkovskiy, Feb 06 2018
Expansion of Delta(q^2)/Delta(q) in powers of q where the discriminant Delta(q) is the g.f. of A000594. - Michael Somos, May 27 2022
From Vaclav Kotesovec, May 08 2023, updated May 16 2023: (Start)
Sum_{n>=1} a(n) / exp(Pi*n) = exp(-Pi) * A292820^24 = 1/8.
Sum_{n>=1} a(n) / exp(3*Pi*n) = exp(-3*Pi) * A292887^24 = (2 + sqrt(3) - sqrt(9 + 6*sqrt(3)))^8 / 512.
Sum_{n>=1} a(n) / exp(4*Pi*n) = exp(-4*Pi) * A292822^24 = 99*sqrt(2)/2048 - 35/512.
Sum_{n>=1} a(n) / exp(5*Pi*n) = exp(-5*Pi) * A292904^24 = (2 + sqrt(5) - sqrt((15 + 7*sqrt(5))/2))^12 / 8.
Sum_{n>=1} a(n) / exp(6*Pi*n) = exp(-6*Pi) * (A363020/A363018)^24 = 385/512 + 7*sqrt(3)/16 - sqrt(74664 + 43134*sqrt(3))/256.
Sum_{n>=1} a(n) / exp(7*Pi*n) = exp(-7*Pi) * (A363119/A363117)^24 = (sqrt(7) - 1 - sqrt(22*sqrt(7) - 56))^3 / (2^(15/2) * (2^(1/4)*sqrt(5 + sqrt(7)) + (56 + 23*sqrt(7))^(1/4))^6).
Sum_{n>=1} a(n) / exp(8*Pi*n) = exp(-8*Pi) * (A292864/A259151)^24 = -8963/512 - 99*sqrt(2)/8 + 9*sqrt(126913704 + 89741542*sqrt(2))/4096.
Sum_{n>=1} a(n) / exp(9*Pi*n) = exp(-9*Pi) * (A363120/A363118)^24 = ((6*(3 + sqrt(3)))^(1/3) - 3)^8 / (8*((3*(6 + 7*sqrt(3) + 3*sqrt(14*sqrt(3) - 15)))^(1/3) - 3)^8).
Sum_{n>=1} a(n) / exp(10*Pi*n) = exp(-10*Pi) * (A363021/A363019)^24 = (5^(1/4) - 1)^24 / 2097152.
Sum_{n>=1} a(n) / exp(Pi*n/2) = exp(-Pi/2) * A292819^24 = 35 + 99/2^(3/2).
Sum_{n>=1} (-1)^(n+1) * a(n) / exp(Pi*n) = 1/64.
Sum_{n>=1} (-1)^(n+1) * a(n) / exp(2*Pi*n) = 99/2^(3/2) - 35.
Sum_{n>=1} (-1)^(n+1) * a(n) / exp(3*Pi*n) = 97/64 - 7*sqrt(3)/8.
Sum_{n>=1} (-1)^(n+1) * a(n) / exp(4*Pi*n) = -5018696 - 3548754*sqrt(2) + (9/2)*sqrt(2487635528172 + 1759023951091*sqrt(2)).
Sum_{n>=1} (-1)^(n+1) * a(n) / exp(7*Pi*n) = 13880161/64 + 81972*sqrt(7) - 9*sqrt(74328271227 + 28093445864*sqrt(7))/8. (End)
The g.f. A(q) satisfies -(16)^2 * A(q^2) = (lambda(q) + lambda(-q)) = (lambda(q)*lambda(-q)), where lambda(q) = 16*q - 128*q^2 + 704*q^3 - ... is the elliptic modular function in powers of the nome q = exp(i*Pi*t), the g.f. of A115977; lambda(q) = k(q)^2, where k(q) = (theta_2(q) / theta_3(q))^2 is the elliptic modulus. - Peter Bala, Sep 26 2023
From Peter Bala, Sep 26 2023: (Start)
A(q^2) = -A(q)*A(-q).
A(q) = lambda(-q)^2/(16*lambda(q)) = lambda(-q)*(lambda(-q) - 1)/16. (End)
G.f. A(x) satisfies 0 = f(A(x), A(-x)) where f(u, v) = u + v + 48*u*v - 4096*u^2*v^2. - Michael Somos, Oct 07 2024

Extensions

More terms from Michael Somos, Nov 24 2001

A292826 Decimal expansion of Product_{k>=1} (1 - exp(-4*Pi*(2*k-1))).

Original entry on oeis.org

9, 9, 9, 9, 9, 6, 5, 1, 2, 6, 5, 7, 6, 4, 3, 7, 4, 8, 5, 9, 3, 1, 4, 4, 2, 9, 7, 5, 1, 8, 7, 6, 7, 3, 2, 2, 7, 3, 8, 6, 0, 0, 8, 5, 8, 7, 9, 1, 5, 8, 1, 9, 1, 5, 7, 1, 5, 6, 2, 5, 9, 9, 1, 5, 3, 3, 3, 5, 9, 5, 3, 9, 4, 1, 3, 6, 2, 0, 2, 7, 9, 7, 4, 6, 4, 8, 9, 0, 5, 6, 0, 6, 2, 3, 2, 5, 7, 4, 0, 3, 1, 2, 8, 5, 7, 2
Offset: 0

Views

Author

Vaclav Kotesovec, Sep 24 2017

Keywords

Examples

			0.999996512657643748593144297518767322738600858791581915715625991533359...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[2^(7/16) / (E^(Pi/6) * (Sqrt[2]-1)^(1/4)), 10, 120][[1]]

Formula

Equals 2^(7/16) / (exp(Pi/6) * (sqrt(2)-1)^(1/4)).
Equals A259150 / A259151.

A292829 Decimal expansion of Product_{k>=1} (1 + exp(-2*Pi*(2*k-1))).

Original entry on oeis.org

1, 0, 0, 1, 8, 6, 7, 4, 4, 9, 2, 5, 6, 3, 0, 4, 4, 3, 5, 1, 0, 5, 4, 3, 2, 7, 5, 0, 5, 1, 0, 7, 3, 2, 1, 5, 0, 1, 5, 9, 8, 8, 5, 3, 9, 5, 4, 8, 3, 7, 8, 9, 4, 0, 5, 6, 6, 4, 4, 9, 8, 7, 6, 1, 1, 7, 9, 8, 1, 8, 2, 4, 3, 7, 7, 1, 2, 6, 0, 3, 1, 0, 6, 6, 4, 0, 2, 8, 0, 3, 6, 9, 7, 2, 8, 8, 6, 5, 1, 5, 4, 6, 7, 6, 5
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 24 2017

Keywords

Examples

			1.001867449256304435105432750510732150159885395483789405664498761179818...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[2^(1/16) / (E^(Pi/12) * (Sqrt[2]-1)^(1/4)), 10, 120][[1]]

Formula

Equals 2^(1/16) / (exp(Pi/12) * (sqrt(2)-1)^(1/4)).
Equals A292821 / A292822.

A292887 Decimal expansion of Product_{k>=1} (1 + exp(-3*Pi*k)).

Original entry on oeis.org

1, 0, 0, 0, 0, 8, 0, 7, 0, 6, 0, 3, 1, 0, 3, 3, 6, 2, 2, 5, 4, 7, 6, 3, 3, 7, 5, 3, 8, 2, 7, 4, 8, 1, 5, 1, 0, 3, 4, 3, 8, 0, 8, 2, 4, 1, 6, 3, 6, 3, 3, 6, 6, 4, 5, 9, 2, 2, 7, 2, 2, 0, 8, 5, 1, 3, 3, 1, 1, 2, 1, 5, 7, 3, 8, 8, 1, 4, 9, 1, 7, 5, 2, 0, 4, 2, 3, 9, 8, 1, 4, 8, 8, 2, 5, 5, 8, 5, 2, 7, 4, 8, 2, 5, 5
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 26 2017

Keywords

Examples

			1.000080706031033622547633753827481510343808241636336645922722085133112...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[(Sqrt[9 + 6*Sqrt[3]] - 2 - Sqrt[3])^(1/3) * E^(Pi/8)/ 2^(3/8), 10, 120][[1]]
    RealDigits[QPochhammer[-1, E^(-3*Pi)]/2, 10, 120][[1]]

Formula

Equals (sqrt(9 + 6*sqrt(3)) - 2 - sqrt(3))^(1/3) * exp(Pi/8) / 2^(3/8).

A292904 Decimal expansion of Product_{k>=1} (1 + exp(-5*Pi*k)).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 1, 5, 0, 7, 0, 1, 7, 5, 0, 2, 5, 0, 0, 2, 3, 9, 8, 9, 4, 9, 3, 8, 6, 9, 8, 7, 1, 4, 6, 7, 9, 7, 3, 7, 6, 1, 0, 0, 6, 4, 3, 0, 5, 0, 7, 4, 0, 5, 6, 9, 0, 1, 9, 9, 9, 8, 8, 5, 2, 0, 8, 8, 7, 1, 3, 4, 4, 2, 6, 9, 4, 9, 7, 1, 7, 6, 1, 8, 7, 2, 8, 7, 4, 6, 7, 3, 2, 5, 8, 5, 1, 0, 0, 2, 8, 5, 0, 4
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 26 2017

Keywords

Examples

			1.000000150701750250023989493869871467973761006430507405690199988520887...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[r/.FindRoot[2^(3/4)*r^6 + 2^(17/8)*E^(5*Pi/24)*r^5 + 2^(5/8)*E^(25*Pi/24)*r - E^(5*Pi/4) == 0, {r, 1}, WorkingPrecision -> 120], 10, 120][[1]]
    RealDigits[QPochhammer[-1, E^(-5*Pi)]/2, 10, 120][[1]]
    RealDigits[Exp[5*Pi/24]*Sqrt[2 + Sqrt[5] - Sqrt[(15 + 7*Sqrt[5])/2]]/2^(1/8), 10, 120][[1]] (* Vaclav Kotesovec, May 13 2023 *)
  • PARI
    polrootsreal(2^(3/4)*'x^6 + 2^(17/8)*exp(5*Pi/24)*'x^5 + 2^(5/8)*exp(25*Pi/24)*'x - exp(5*Pi/4))[2] \\ Charles R Greathouse IV, Mar 04 2018

Formula

Root r of the equation 2^(3/4)*r^6 + 2^(17/8)*exp(5*Pi/24)*r^5 + 2^(5/8)*exp(25*Pi/24)*r - exp(5*Pi/4) = 0.
Equals exp(5*Pi/24) * sqrt(2 + sqrt(5) - sqrt((15 + 7*sqrt(5))/2))/2^(1/8). - Vaclav Kotesovec, May 13 2023
Showing 1-9 of 9 results.