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 26 results. Next

A078434 Decimal expansion of zeta(3/2).

Original entry on oeis.org

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

Views

Author

Robert G. Wilson v, Dec 30 2002

Keywords

Examples

			2.6123753486854883433485675679240716305708006524000634075733...
		

Crossrefs

Programs

Formula

Equals (2/sqrt(Pi))*Integral_{x>=0} sqrt(x)/(exp(x)-1) dx. - Jean-François Alcover, Nov 12 2013
Equals Gamma(-1/2)*zeta(-1/2)*tau(-1/2) where tau(s) = (2*Pi*i)^(-s) + (-2*Pi*i)^(-s). This follows from the functional equation of the Riemann zeta function. (Cf. A059750, A211113, A019707). - Peter Luschny, May 13 2020
Equals -4*Pi*zeta(-1/2) = 10 * A019694 * A211113. - Amiram Eldar, May 29 2021

A113024 Decimal expansion of Sum_{k>=1} -(-1)^k/sqrt(k).

Original entry on oeis.org

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

Views

Author

Robert G. Wilson v, Oct 11 2005

Keywords

Examples

			1 - 1/sqrt(2) + 1/sqrt(3) - 1/sqrt(4) + 1/sqrt(5) - 1/sqrt(6) + 1/sqrt(7) ... =
0.60489864342163037024726591423595549975976254513024738037854664808...
		

References

  • Stephen Fletcher Hewson, A Mathematical Bridge: An Intuitive Journey In Higher Mathematics, World Scientific, NJ, 2003, p. 83.

Crossrefs

Programs

  • Maple
    Zeta(0,1/2,1/2); evalf(%) ; # R. J. Mathar, Dec 17 2024
  • Mathematica
    RealDigits[(1 - Sqrt[2])Zeta[1/2], 10, 111][[1]]
  • PARI
    (1-sqrt(2))*zeta(1/2) \\ G. C. Greubel, Apr 09 2018

Formula

Equals (1-sqrt(2))*zeta(1/2) = (-1+A002193) * A059750.
A265162/A113024 = gamma/2 + Pi/4 - (1/2 + sqrt(2))*log(2) + log(Pi)/2, where gamma is the Euler-Mascheroni constant A001620. - Vaclav Kotesovec, Dec 03 2015
Equals -zeta(1/2, 1/2). - Peter Luschny, Nov 03 2020

A088537 Decimal expansion of Madelung's constant M2.

Original entry on oeis.org

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

Views

Author

Benoit Cloitre, Nov 16 2003

Keywords

Examples

			M2 = -1.61554262671282472386792333275861809...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, pp. 76-81.

Crossrefs

Cf. A059750.

Programs

  • Maple
    M2:=evalf(4*(sqrt(2)-1)*Zeta(1/2)*sum('(-1)^n/sqrt(2*n+1)','n'=0..infinity),120); # Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 10 2009
  • Mathematica
    (2-2*I)*(Sqrt[2]-1)*Zeta[1/2]*(PolyLog[1/2, -I]-Zeta[1/2, 1/4]) // Re // RealDigits[#, 10, 105]& // First (* Jean-François Alcover, Feb 15 2013 *)
  • PARI
    DirBet=sumalt(n=0, (-1)^n/sqrt(2*n+1)); print(4.0*(sqrt(2)-1)*zeta(0.5)*DirBet) ; \\ R. J. Mathar, Jul 20 2007

Formula

M2 = Sum_{ -oo < i < oo, -oo < j < oo, (i,j) != (0,0) } (-1)^(i + j)/sqrt(i^2 + j^2).
M2 = 4*(sqrt(2) - 1)*zeta(1/2)*beta(1/2) (beta=Dirichlet beta function).

Extensions

More terms from R. J. Mathar, Jul 20 2007
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 10 2009

A247041 Decimal expansion of zeta(5/2).

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Sep 10 2014

Keywords

Comments

Zeta(5/2) appears in the expression of the 6th Madelung constant (A247040).

Examples

			1.3414872572509171797567696933486121366230376295059865...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Sections 1.10 Madelung's constant, p. 77.

Crossrefs

Programs

  • Mathematica
    RealDigits[Zeta[5/2], 10, 102] // First
  • PARI
    zeta(5/2) \\ Michel Marcus, Feb 23 2023

A090734 Decimal expansion of 4th Madelung constant (negated).

Original entry on oeis.org

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

Views

Author

Benoit Cloitre, Jan 18 2004

Keywords

Examples

			-1.83939908404504706624730547956723047642278359481773...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge, 2003, p. 77.

Crossrefs

Programs

  • Mathematica
    RealDigits[8*(5 - 3*Sqrt[2])*Zeta[1/2]*Zeta[-1/2], 10, 120][[1]] (* Amiram Eldar, May 26 2023 *)
  • PARI
    8*(5-3*sqrt(2))*zeta(1/2)*zeta(-1/2) \\ Charles R Greathouse IV, Jun 07 2016

Formula

M_4 = -8*(5-3*sqrt(2))*zeta(1/2)*zeta(-1/2) = -8 *(A157122-6) * A059750 * A211113.

A247040 Decimal expansion of M_6, the 6th Madelung constant.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Sep 10 2014

Keywords

Examples

			-1.9655570390090782813123135557351853678689767284464645117...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Sections 1.10 Madelung's constant, p. 77.

Crossrefs

Programs

  • Mathematica
    beta[x_] := (Zeta[x, 1/4] - Zeta[x, 3/4])/4^x; M6 = (3/Pi^2)*(4*(Sqrt[2]-1)*Zeta[1/2]*beta[5/2] - (4*Sqrt[2]-1)*Zeta[5/2]*beta[1/2]); RealDigits[M6, 10, 104][[1]]
  • PARI
    th4(x)=1+2*sumalt(n=1, (-1)^n*x^n^2)
    intnum(x=0, [oo, 1], (th4(exp(-x))^6-1)/sqrt(Pi*x)) \\ Charles R Greathouse IV, Jun 07 2016
    
  • PARI
    th4(x)=1+2*sumalt(n=1, (-1)^n*x^n^2)
    intnum(x=0, [oo, 1], (th4(exp(-x))^6-1)/sqrt(Pi*x)) \\ Charles R Greathouse IV, Jun 06 2016

Formula

M6 = (3/Pi^2)*(4*(sqrt(2)-1)*zeta(1/2)*beta(5/2) - (4*sqrt(2)-1)*zeta(5/2)*beta(1/2)), where beta is Dirichlet's "beta" function.

A054040 a(n) terms of series {1/sqrt(j)} are >= n.

Original entry on oeis.org

1, 3, 5, 7, 10, 14, 18, 22, 27, 33, 39, 45, 52, 60, 68, 76, 85, 95, 105, 115, 126, 138, 150, 162, 175, 189, 202, 217, 232, 247, 263, 280, 297, 314, 332, 351, 370, 389, 409, 430, 451, 472, 494, 517, 540, 563, 587, 612, 637, 662, 688, 715, 741, 769, 797, 825
Offset: 1

Views

Author

Asher Auel, Apr 13 2000

Keywords

Comments

In many cases the first differences have the form {2k, 2k, 2k, 2k+1} (A004524). In such cases the second differences are {0, 0, 1, 1}. See A082915 for the exceptions. In as many as these, the first differences have the form {2k-1, 2k-1, 2k-1, 2k}. - Robert G. Wilson v, Apr 18 2003 [Corrected by Carmine Suriano, Nov 08 2013]
a(100)=2574, a(1000)=250731 & a(10000)=25007302 which differs from Sum{i=4..104}A004524(i)=2625, Sum{i=4..1004}A004524(i)=251250 & Sum{i=4..10004}A004524(i)=25012500. - Robert G. Wilson v, Apr 18 2003
A054040(n) <= A011848(n+2), A054040(10000)=25007302 and A011848(n+2)=25007500. - Robert G. Wilson v, Apr 18 2003

Examples

			Let b(k) = 1 + 1/sqrt(2) + 1/sqrt(3) + ... + 1/sqrt(k):
.k.......1....2.....3.....4.....5.....6.....7
-------------------------------------------------
b(k)...1.00..1.71..2.28..2.78..3.23..3.64..4.01
For A019529 we have:
n=0: smallest k is a(0) = 1 since 1.00 > 0
n=1: smallest k is a(1) = 2 since 1.71 > 1
n=2: smallest k is a(2) = 3 since 2.28 > 2
n=3: smallest k is a(3) = 5 since 3.23 > 3
n=4: smallest k is a(4) = 7 since 4.01 > 4
For this sequence we have:
n=1: smallest k is a(1) = 1 since 1.00 >= 1
n=2: smallest k is a(2) = 3 since 2.28 >= 2
n=3: smallest k is a(3) = 5 since 3.23 >= 3
n=4: smallest k is a(4) = 7 since 4.01 >= 4
		

Crossrefs

See A019529 for a different version.

Programs

  • Mathematica
    f[n_] := Block[{k = 0, s = 0}, While[s < n, k++; s = N[s + 1/Sqrt[k], 50]]; k]; Table[f[n], {n, 1, 60}]
  • PARI
    a(n)=if(n<0,0,t=1;z=1;while(zBenoit Cloitre, Sep 23 2012

Formula

Let f(n) = (1/4)*(n^2-2*zeta(1/2)*n) then we have a(n) = f(n) + O(1). More precisely we claim that for n >= 2 we have a(n) = floor(f(n)+c) where c > Max{a(n)-f(n) : n>=1} = a(153) - f(153) = 1.032880076066608813953... and we believe we can take c = 1.033. - Benoit Cloitre, Sep 23 2012

Extensions

Definition and offset modified by N. J. A. Sloane, Sep 01 2009

A261804 Decimal expansion of zeta(7/2).

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Sep 01 2015

Keywords

Comments

Zeta(7/2) appears in the expression of the 8th Madelung constant (A261805).

Examples

			1.126733867317056646427812491854984272221996957403602963842396...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Sections 1.10 Madelung's constant, p. 77.

Crossrefs

Programs

A134469 Decimal expansion of -zeta(1/2)/sqrt(2*Pi).

Original entry on oeis.org

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

Views

Author

Hans J. H. Tuenter, Oct 27 2007

Keywords

Comments

This number is the limiting expected overshoot over a boundary for the sum of independent and identically distributed normal variables with unit variance, as their positive mean approaches zero. It has applications in sequential analysis.

Examples

			0.58259715793901067020517716418763115472909387019865...
		

References

  • Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, 2003, Section 5.9, p. 326.

Crossrefs

Cf. A134470 (continued fraction), A134471 (Numerators of continued fraction convergents), A134472 (Denominators of continued fraction convergents).

Programs

  • Maple
    Digits:=100; evalf(-Zeta(1/2)/sqrt(2*Pi));
  • Mathematica
    RealDigits[-Zeta[1/2]/Sqrt[2*Pi], 10, 100][[1]] (* G. C. Greubel, Mar 27 2018 *)
  • PARI
    -zeta(1/2)/sqrt(2*Pi) \\ Charles R Greathouse IV, Mar 10 2016

Formula

-zeta(1/2)/sqrt(2*Pi)= A059750/A019727.

Extensions

More decimals from Vaclav Kotesovec, Mar 21 2016

A114875 Decimal expansion of -zeta'(1/2).

Original entry on oeis.org

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

Views

Author

Eric W. Weisstein, Jan 03 2006

Keywords

Examples

			3.92264613920915172747153144671459951373032397150650...
		

Crossrefs

Programs

Formula

Equals ((2*gamma + Pi + 2*log(8*Pi))*zeta(1/2))/4, where gamma is Euler's constant (A001620).
Showing 1-10 of 26 results. Next