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 1-10 of 13 results. Next

A248916 Decimal expansion of gamma = 8*lambda^2, a critical threshold of a boundary value problem, where lambda is Laplace's limit constant A033259.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Oct 16 2014

Keywords

Comments

The boundary value problem y''(x) + c*exp(y(x)) = 0, y(0) = y(1) = 0 and c > 0, has 0, 1 or 2 solutions when c > gamma, c = gamma and c < gamma, respectively. [After Steven Finch]

Examples

			3.5138307191251612062078370932388235871...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 4.8 Laplace limit constant, p. 266.

Crossrefs

Programs

  • Mathematica
    digits = 104; lambda = x /. FindRoot[x Exp[Sqrt[1 + x^2]]/(1 + Sqrt[1 + x^2]) == 1, {x, 1}, WorkingPrecision -> digits + 5]; gamma = 8*lambda^2; RealDigits[gamma, 10, digits] // First

A345736 Decimal expansion of the surface area of the catenoid-shaped soap film between two parallel coaxial unit-radius circular rings whose distance between their centers is maximal (2*A033259).

Original entry on oeis.org

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

Views

Author

Amiram Eldar, Jun 25 2021

Keywords

Examples

			7.53780320580457797882651822069283034551193592152611...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[2 * Pi * x /. FindRoot[x == Coth[x], {x, 1}, WorkingPrecision -> 120], 10, 100][[1]]

Formula

Equals 2*Pi*A085984.

A085984 Decimal expansion of solution to e^x*(-1 + x) = (1 + x)/e^x.

Original entry on oeis.org

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

Views

Author

Eric W. Weisstein, Jul 06 2003

Keywords

Comments

This constant can also be defined as the root of coth x = x, as this equation and the above are equivalent. - Carl R. White, Dec 09 2003. Also the root of x*tanh x = 1. - N. J. A. Sloane, May 07 2020
This constant is also the point on the parametric tractrix (t - tanh(t), sech(t)) the least distant from the origin. - Michael Clausen, Feb 18 2013
This constant also equals sqrt(lambda^2+1), where lambda is the Laplace limit constant A033259. - Jean-François Alcover, Sep 08 2014, after Steven Finch.
For each of the real symmetric n X n matrices M defined by M(i,j) = max(i,j) with n >= 2, there exist n-1 negative eigenvalues < -1/4 and only one positive eigenvalue lambda(n) such that n^2/2 < lambda(n) < n^2. Indeed, when n tends to infinity, lambda(n) ~ n^2/(this constant)^2 (see reference O. Carton et al.). For n = 2, the positive eigenvalue is (3+sqrt(17))/2 [A178255]. - Bernard Schott, Mar 13 2020

Examples

			1.1996786402577338339163698486411419442614587884186072...
		

References

  • O. Carton, L. Rosaz, M. Zeitoun, Problèmes corrigés de Mathématiques posés au Concours de Mines/Ponts, Tome 5, Ellipses, 1992; Problème Mines-Ponts 1991 - Options M, P', TA - Epreuve pratique p. 125.
  • Steven R. Finch, Mathematical constants, Volume 94, Encyclopedia of mathematics and its applications, Cambridge University Press, 2003, p. 268.
  • Jerome Spanier and Keith B. Oldham, "Atlas of Functions", Hemisphere Publishing Corp., 1987, chapter 30, equation 30:10:9 at page 283.

Crossrefs

Cf. A003957 (x = cos(x)), A009379, A033259, A069855, A209289.

Programs

  • Mathematica
    RealDigits[ x /. FindRoot[ Coth[x] == x, {x, 1}, WorkingPrecision -> 102]] // First (* Jean-François Alcover, Feb 08 2013 *)
    1+2 NSum[LaguerreL[n-1,1,4 n]/n Exp[-2 n],{n,1,Infinity}] //
      (* Aaron Hendrickson, Mar 17 2021 *)
  • PARI
    solve(u=1,2,tanh(u)-1/u)  /* type e.g. \p99 to get 99 digits; M. F. Hasler, Feb 01 2011 */

Formula

Equals 1 + 2*Sum_{n>=1} (Laguerre(n-1,1,4n)/n)*e^(-2n) (see Mathematics Stack Exchange in Links). - Aaron Hendrickson, Mar 17 2022

A033260 Continued fraction for Laplace's limit constant.

Original entry on oeis.org

0, 1, 1, 1, 27, 1, 1, 1, 8, 2, 154, 2, 4, 1, 5, 1, 1, 2, 1601, 2, 63, 1, 2, 12, 17, 9, 2, 1, 1, 57, 1, 6, 2, 4, 3, 10, 1, 6, 2, 1, 3, 4, 2, 1, 31, 3, 6, 1, 1, 4, 2, 1, 1, 1, 1, 1, 1, 14, 1, 4, 1, 2, 2, 1, 97, 1, 52, 2, 4, 1, 1, 5, 13, 1, 1, 3, 6, 2, 3, 3, 2, 2, 1, 1, 2, 28, 2, 3, 1, 4, 2, 1, 4
Offset: 0

Views

Author

Keywords

References

  • S. R. Finch, Mathematical Constants, Cambridge, 2003, pp. 266-268.

Crossrefs

Cf. A033259 (decimal expansion), A033261, A033262, A033263.

Programs

  • Mathematica
    ContinuedFraction[Sqrt[x^2-1]/.FindRoot[x==Coth[x], {x,1}, WorkingPrecision -> 250], 121] (* G. C. Greubel, Dec 13 2024 *)

Extensions

Offset changed by Andrew Howroyd, Jul 04 2024

A033261 Position of first occurrence of n in the continued fraction for the Laplace's limit constant.

Original entry on oeis.org

1, 9, 34, 12, 14, 31, 100, 8, 25, 35, 101, 23, 72, 57, 750, 270, 24, 365, 363, 482, 191, 642, 821, 541, 393, 632, 4, 85, 2049, 617, 44, 201, 941, 182, 206, 862, 3104, 1295, 2122, 258, 1576, 5551, 158, 3353, 3870, 114, 506, 1669, 9646, 1127, 445, 66, 1804
Offset: 1

Views

Author

Keywords

Comments

The continued fraction expansion is indexed [a_0; a_1, a_2, a_3, ...].

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 266-268.

Crossrefs

Formula

A033260(a(n)) = n. - Andrew Howroyd, Sep 12 2024

Extensions

More terms from Michel ten Voorde Jun 20 2003
Terms decreased by 1 for consistency with offset change in A033260 by Andrew Howroyd, Sep 12 2024

A033262 Incrementally largest terms in the continued fraction for Laplace's limit constant.

Original entry on oeis.org

1, 27, 154, 1601, 2135, 4132, 7166, 8391, 10970, 34639, 748645, 1005174
Offset: 1

Views

Author

Keywords

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 266-268.

Crossrefs

Extensions

More terms from Michel ten Voorde Jun 20 2003

A033263 Positions of the incrementally largest terms in the continued fraction for Laplace's limit constant.

Original entry on oeis.org

1, 4, 10, 18, 1800, 2079, 6560, 7688, 11310, 12437, 24708, 63577
Offset: 1

Views

Author

Keywords

Comments

The continued fraction expansion is indexed [a_0; a_1, a_2, a_3, ...].

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 266-268.

Crossrefs

Formula

A033260(a(n)) = A033262(n). - Andrew Howroyd, Sep 12 2024

Extensions

More terms from Michel ten Voorde Jun 20 2003
Terms decreased by 1 for consistency with offset change in A033260 by Andrew Howroyd, Sep 12 2024

A240358 Decimal expansion of 'c', a constant linked to an estimate of density of zeros of an entire function of exponential type.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Apr 04 2014

Keywords

Examples

			1.508879561538319928909884488160578573694278589...
		

Crossrefs

Cf. A033259.

Programs

  • Mathematica
    FindRoot[Log[c + Sqrt[c^2 + 1]] == Sqrt[1 + 1/c^2], {c, 3/2}, WorkingPrecision -> 100][[1, 2]] // RealDigits[#, 10, 100]& // First

Formula

Solution to log(c + sqrt(c^2 + 1)) = sqrt(1 + 1/c^2).
Equals 1/A033259. - Robert FERREOL, Jun 16 2025

A249136 Decimal expansion of the largest constant 'beta' for which there exists a solution to the differential equation y''(x)+exp(y(x))=0, with y(0)=y(beta)=0.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Oct 22 2014

Keywords

Examples

			1.874521464034264187600324820470264120147219398917056...
		

Crossrefs

Programs

  • Mathematica
    lambda = x /. FindRoot[x*Exp[Sqrt[1 + x^2]]/(1 + Sqrt[1 + x^2]) == 1, {x, 1}, WorkingPrecision -> 102]; beta = Sqrt[8]*lambda; RealDigits[beta] // First

Formula

beta = sqrt(8)*lambda, where lambda is A033259, the Laplace limit constant 0.66274...
Equals sqrt(A248916). - Hugo Pfoertner, Dec 19 2024

A253545 Decimal expansion of r = 0.527697..., a boundary ratio separating catenoid and Goldschmidt solutions in the minimal surface of revolution problem.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Apr 21 2015

Keywords

Comments

Consider two circular frames each of diameter D and with a separation of d.
If d/D < r = 0.527697..., then a catenoid gives the absolute minimum area.
If r < d/D < L = 0.66274... (Laplace limit), there are 3 minimal surfaces of revolution passing through the frames: 2 catenoids and the so-called Goldschmidt discontinuous solution consisting of the 2 disks.
If d/D > L, there remains only the Goldschmidt solution.

Examples

			0.5276973969625715285724233433631805779688537906314195417222751595...
		

Crossrefs

Cf. A033259 (Laplace limit), A202357.

Programs

  • Mathematica
    digits = 105; u0 = u /. FindRoot[u*Sqrt[u^2-1] + ArcCosh[u] - u^2 == 0, {u, 6/5}, WorkingPrecision -> digits+5];  r = ArcCosh[u0]/u0; RealDigits[r, 10, digits] // First

Formula

arccosh(u)/u, where u = 1.21136... is solution to u*sqrt(u^2-1) + arccosh(u) - u^2 = 0.
Solution of 2*cosh((x^2+1)/2) = x+1/x. - Robert FERREOL, Feb 07 2019
Equals sqrt(A202357). - Hugo Pfoertner, Dec 21 2024
Showing 1-10 of 13 results. Next