A282823 -id:A282823 - cp's OEIS frontend

A006752 Decimal expansion of Catalan's constant 1 - 1/9 + 1/25 - 1/49 + 1/81 - ...

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

Offset: 0

N. J. A. Sloane

Usually denoted by G.

With the k-th appended term being 2*3*...*(2+k-2)*2^k*(2^k-1)*Bern(k) / (2*k!*(J^(k+2-1))). Bern(k) is a Bernoulli number and J is a large number of the form 4n + 1. See equation 3:3:7 in Spanier and Oldham. - Harry J. Smith, May 07 2009

			0.91596559417721901505460351493238411077414937428167213426649811962176301977...

Miklos Bona, editor, Handbook of Enumerative Combinatorics, CRC Press, 2015, pages 57, 554.
Steven R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, pp. 53-59.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Jerome Spanier and Keith B. Oldham, An Atlas of Functions, 1987, equations 1:7:3, 3:3:7.

Harry J. Smith, Table of n, a(n) for n = 0..20000
Milton Abramowitz and Irene A. Stegun, editors, Catalan's constant, Handbook of Mathematical Functions, December 1972, p. 807, 23.2.21 for n=2.
Victor Adamchik, 33 representations for Catalan's constant.
David H. Bailey, Jonathan M. Borwein, Andrew Mattingly, and Glenn Wightwick, The Computation of Previously Inaccessible Digits of Pi^2 and Catalan's Constant, Notices AMS, 60 (No. 7 2013), 844-854.
Peter Bala, New series for old functions.
David M. Bradley, Representations of Catalan's constant, 2001.
Eugène-Charles Catalan, Mémoire sur la transformation des séries et sur quelques intégrales définies, Mémoires de l'Académie royale de Belgique, 1867, Vol. 33, pp. 1-50.
Sarth Chavan and Christophe Vignat, A Triple Integral representation of Catalan's constant, arXiv:2105.11771 [math.NT], 2021.
Greg Fee, Catalan's Constant to 300000 digits, Project Gutenberg, 1996.
G. J. Fee, Computation of Catalan's constant using Ramanujan's formula, in Proc. Internat. Symposium on Symbolic and Algebraic Computation (ISSAC '90). 1990, pp. 157-160.
Philippe Flajolet and Ilan Vardi, Zeta function expansions of some classical constants.
Werner Hürlimann, Exact and Asymptotic Evaluation of the Number of Distinct Primitive Cuboids, Journal of Integer Sequences, Vol. 18 (2015), Article 15.2.5.
Yasuyuki Kachi and Pavlos Tzermias, Infinite products involving zeta(3) and Catalan's constant, Journal of Integer Sequences, Vol. 15 (2012), #12.9.4.
F. M. S. Lima, A rapidly converging Ramanujan-type series for Catalan's constant, arXiv:1207.3139v1 [math.NT], Jul 13 2012.
A. Lupas, Formulae for some classical constants, in Proceedings of ROGER-2000, 2000. [Local copy]
David Naccache and Ofer Yifrach-Stav, On Catalan Constant Continued Fractions, arXiv:2210.15669 [cs.SC], 2022.
T. Papanikolaou and G. Fee, Catalan's Constant [Ramanujan's Formula] to 1,500,000 places, Project Gutenberg, 1997.
Kh. Hessami Pilehrood and Tatiana Hessami Pilehrood, Series acceleration formulas for beta values, Discr. Math. Theor. Comp. Sci. 12 (2) (2010) 223-236.
Simon Plouffe, Generalized expansions of real numbers, 2006.
Xiaohan Wang, The Barnes G-function and the Catalan Constant, Kyushu Journal of Mathematics, Vol. 67 (2013) No. 1, pp. 105-116.
Eric Weisstein's World of Mathematics, Catalan's Constant.
Eric Weisstein's World of Mathematics, Catalan's Constant Digits.
Eric Weisstein's World of Mathematics, Hurwitz Zeta Function.
Eric Weisstein's World of Mathematics, Trigamma Function
Wikipedia, Catalan's constant.
Sheldon Yang, Some properties of Catalan's constant G, Int. J. Math. Educ. Sci. Technol 23 (4) (1992) 549-556.
David G. Zeitoun and Thierry Dana-Picard, A half-automated study of a 2-parameter family of integrals, arXiv:2412.11726 [math.CO], 2024. See p. 8.

Cf. A014538, A104338, A153069, A153070, A054543, A118323, A294970/A294971.

R:= RealField(100); Catalan(R); // G. C. Greubel, Aug 21 2018

evalf(Catalan) ; # R. J. Mathar, Apr 09 2013

nmax = 1000; First[RealDigits[Catalan, 10, nmax]] (* Stuart Clary, Dec 17 2008 *)
Integrate[ArcTan[x]/x, {x, 0, 1}] (* N. J. A. Sloane, May 03 2013 *)
N[Im[PolyLog[2, I]], 100] (* Peter Luschny, Oct 04 2019 *)

{ mydigits=20000; default(realprecision, mydigits+80); s=1.0; n=5*mydigits; j=4*n+1; si=-1.0; for (i=3, j-2, s+=si/i^2; si=-si; i++; ); s+=0.5/j^2; ttk=4.0; d=4.0*j^3; xk=2.0; xkp=xk; for (k=2, 100000000, term=(ttk-1)*ttk*xkp; xk++; xkp*=xk; if (k>2, term*=xk; xk++; xkp*=xk; ); term*=bernreal(k)/d; sn=s+term; if (sn==s, break); s=sn; ttk*=4.0; d*=(k+1)*(k+2)*j^2; k++; ); x=10*s; for (n=0, mydigits, d=floor(x); x=(x-d)*10; write("b006752.txt", n, " ", d)); } /* Beta(2) = 1 - 1/3^2 + 1/5^2 - ... - 1/(J-2)^2 + 1/(2*J^2) + 2*Bern(0)/(2*J^3) - 2*3*4*Bern(2)/J^5 + ...  */

default(realprecision,1000+2); /* 1000 terms */
s=sumalt(n=0,(-1)^n/(2*n+1)^2);
v=Vec(Str(s)); /* == ["0", ".", "9", "1", "5", "9", "6", ...*/
vector(#v-2,n,eval(v[n+2]))
/* Joerg Arndt, Aug 25 2011 */

Catalan \\ Charles R Greathouse IV, Nov 20 2011

(zetahurwitz(2,1/4)-Pi^2)/8 \\ Charles R Greathouse IV, Jan 30 2018

lerchphi(-1, 2, 1/2)/4 \\ Charles R Greathouse IV, Jan 30 2025

G = Integral_{x=0..1} arctan(x)/x dx.
G = Integral_{x=0..1} 3*arctan(x*(1-x)/(2-x))/x dx. - Posting to Number Theory List by James Mc Laughlin, Sep 27 2007
G = (zeta(2,1/4)- zeta(2,3/4))/16. - Gerry Martens, May 27 2011 [With the Hurwitz zeta function zeta.]
G = (1/2)*Sum_{n>=0} (-1)^n * ((3*n+2)*8^n) / ((2*n+1)^3*C(2*n,n)^3) (from the Lima 2012 reference).
G = (-1/64)*Sum_{n>=1} (-1)^n * (2^(8*n) * (40*n^2-24*n+3)) / (n^3 * (2*n-1) * C(2*n,n) * C(4*n,2*n)^2) (from the Lupas 2000 reference).
G = phi(-1, 2, 1/2)/4 = A247685/4, where phi is Lerch transcendent. - Jean-François Alcover, Mar 28 2013
G = (1/2)*Integral_{x=0..Pi/2} log(cot(x)+csc(x)) dx. - Jean-François Alcover, Apr 11 2013 [see the Adamchik link]
G = -Integral_{x=0..1} (log x)/(1+x^2) dx = Integral_{x>=1} (log x)/(1+x^2) dx. - Clark Kimberling, Nov 04 2016
G = (Zeta(2, 1/4) - Pi^2)/8 = (Psi(1, 1/4) - Pi^2)/8 = (A282823-Pi^2)/8, with the Hurwitz zeta function and the trigamma function Psi(1, z). For the partial sums of the series given in the name see A294970/A294971. - Wolfdieter Lang, Nov 15 2017
Equals Im(Li_{2}(i)). - Peter Luschny, Oct 04 2019
Equals -Integral_{x=0..Pi/4} log(tan(x)) dx. - Amiram Eldar, Jun 29 2020
Equals (1/2)*Integral_{x=0..1} K(x) dx = -1/2 + Integral_{x=0..1} E(x) dx, where K(k) and E(k) are the complete elliptic integrals of the first and second kind, respectively, as a functions of the elliptic modulus k. - Gleb Koloskov, Jun 25 2021
From Peter Bala, Dec 08 2021: (Start)
G = 1/2 + 4*Sum_{n >= 1} (-1)^(n+1)*n/(4*n^2 - 1)^2 = -13/18 + (2^7)*3*Sum_{n >= 1} (-1)^(n+1)*n/((4*n^2 - 1)^2*(4*n^2 - 9)^2) = -3983/1350 + (2^15)*3*5*Sum_{n >= 1} (-1)^(n+1)*n/((4*n^2 - 1)^2*(4*n^2 - 9)^2*(4*n^2 - 25)^2).
G = 3/2 - 16*Sum_{n >= 1} (-1)^(n+1)*n/(4*n^2 - 1)^3 = 401/6 - (2^13)*(3^3)*Sum_{n >= 1} (-1)^n*n/((4*n^2 - 1)^3*(4*n^2 - 9)^3) = 5255281/1350 - (2^25)*(3^3)*(5^3)*Sum_{n >= 1} (-1)^(n+1)*n/((4*n^2 - 1)^3*(4*n^2 - 9)^3*(4*n^2 - 25)^3). (End)
From Amiram Eldar, Jan 07 2024: (Start)
Equals beta(2), where beta is the Dirichlet beta function.
Equals Product_{p prime >= 3} (1 - (-1)^((p-1)/2)/p^2)^(-1). (End)
Equals 2*Integral_{x=0..Pi/4} log(2*cos(x)) dx = -2*Integral_{x=0..Pi/4} log(2*sin(x)) dx (see Finch). - Stefano Spezia, Nov 14 2024
Equals Integral_{x=0..Pi/4} log((1 + tan(x))/(1 - tan(x))) dx. - Kritsada Moomuang, Jun 03 2025

More terms from Larry Reeves (larryr(AT)acm.org), May 28 2002

A173947 a(n) = numerator of (Zeta(2, 1/4) - Zeta(2, n+1/4)), where Zeta is the Hurwitz Zeta function.

Original entry on oeis.org

0, 16, 416, 34096, 5794624, 1680121936, 82501802464, 2065646660464, 1739147340740224, 210617970218777104, 288533264855755545376, 485294472126860897387056, 485518650207447822251456

Offset: 0

Artur Jasinski, Mar 03 2010

For A173947/16 see A173949.

a(n+1)/A173948(n+1) =: r(n) = (Zeta(2, 1/4) - Zeta(2, n + 5/4)), the partial sum Sum_{k=0..n} 1/(k + 1/4)^2, n >= 0. The limit is Zeta(2, 1/4) = A282823 = 16*A222183. - Wolfdieter Lang, Nov 14 2017

G. C. Greubel, Table of n, a(n) for n = 0..250
Eric Weisstein's World of Mathematics, Hurwitz Zeta Function
Eric Weisstein's World of Mathematics, Trigamma Function

Cf. A006752, A120268, A173945, A173948 (denominators), A173949.

[1] cat [Numerator((&+[1/(4*k+1)^2: k in [0..n-1]])): n in [1..20]]; // G. C. Greubel, Aug 22 2018

r := n -> Psi(1, 1/4) - Zeta(0, 2, n+1/4):
seq(numer(simplify(r(n))), n=0..13); # Peter Luschny, Nov 14 2017

Table[Numerator[FunctionExpand[8*Catalan + Pi^2 - Zeta[2, (4*n + 1)/4]]], {n, 0, 20}] (* Vaclav Kotesovec, Nov 14 2017 *)
Numerator[Table[128*n*Sum[(1 + 4*k + 2*n) / ((1 + 4*k)^2*(1 + 4*k + 4*n)^2), {k, 0, Infinity}], {n, 0, 20}]] (* Vaclav Kotesovec, Nov 14 2017 *)
Numerator[Table[16*Sum[1/(4*k + 1)^2, {k, 0, n - 1} ], {n, 0, 20}]] (* Vaclav Kotesovec, Nov 14 2017 *)

for(n=0,20, print1(numerator(sum(k=0,n-1, 1/(4*k+1)^2)), ", ")) \\ G. C. Greubel, Aug 22 2018

a(n) = numerator of 8*Catalan + Pi^2 - Zeta(2, (4 n + 1)/4), with the Catalan constant given in A006752.

a(n) = numerator(r(n)) with r(n) = Zeta(2, 1/4) - Zeta(2, n + 1/4), with the Hurwitz Zeta function (see the name). With Zeta(2, 1/4) = Psi(1, 1/4) = 8*Catalan + Pi^2 this is the preceding formula, where Psi(1, z) is the Trigamma function. - Wolfdieter Lang, Nov 14 2017

Name simplified and offset set to 0 by Peter Luschny, Nov 14 2017

A332645 Decimal expansion of Sum_{n>=1} 1/z(n)^2 where z(n) is the imaginary part of the n-th nontrivial zero of the Riemann zeta function.

Original entry on oeis.org

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

Offset: 0

Artur Jasinski, Feb 18 2020

			0.0231049931154189707889338104303390140033817603974220901231825...

J. P. Gram, "Note sur le calcul de la fonction zeta(s) de Riemann", Det Kgl. Danske Vid. Selsk. Overs., 1895, pp. 303-308. p.307 (16 decimal digits).
Charles Jean De La Vallée Poussin, Sur La Fonction de Riemann Et Le Nombre Des Nombres Premiers Inférieurs à Une Limite Donnee, 1899.

Jesús Guillera, Some sums over the non-trivial zeros of the Riemann zeta function, arXiv:1307.5723v7 [math.NT], 2013-2014; see p.9 eq.(21).
Kano Kono, Vieta's Formulas on Completed Riemann Zeta, Alien's Mathematics p. 13 eq. 2.3(2).
E. Landau, Handbuch der Lehre von der Verteilung der Primzahlen I, 1909, pp. 310-342.
J. J. Y. Liang and John Todd, The Stieltjes Constants, Journal of Research of the National Bureau of Standards, 1972, pp. 175-176.
André Voros, Zeta functions for the Riemann zeros, arXiv:math/0104051 [math.CV], 2002-2003, p.25 Table 2.
André Voros, Zeta functions for the Riemann zeros, 2001(2008) p.20 Table 1.
André Voros, Zeta functions for the Riemann zeros, Annales de l'Institut Fourier, Tome 53 (2003) no. 3, p. 665-699.
André Voros, Zeta functions over Zeros of the Zeta functions, 2010, p. 153.

Cf. A006752, A074760, A332614.

evalf((-32 - log(Pi)^2 + Psi(0, 1/4)^2 + Psi(1, 1/4) + 4*(Psi(0, 1/4) * Zeta(1, 1/2) + Zeta(2, 1/2)) / Zeta(1/2)) / 8, 120); # Vaclav Kotesovec, Feb 19 2020

Join[{0}, RealDigits[N[-4 + Catalan + Pi^2/8 + (Zeta''[1/2]/Zeta[1/2] - (Zeta'[1/2] / Zeta[1/2])^2)/2, 105]][[1]]]
N[SeriesCoefficient[Log[s*(s-1)*Pi^(-s/2)*Gamma[s/2]*Zeta[s]/2], {s, 1/2, 2}], 105] (* Vaclav Kotesovec, Feb 19 2020 *)

Equals -4 + G + Pi^2/8 + (1/2)(zeta''(1/2)/zeta(1/2) - (zeta'(1/2)/zeta(1/2))^2) where G is the Catalan constant A006752.
Equals G - 4 + (Pi^2 - (gamma + Pi/2 + log(8*Pi))^2) / 8 + zeta''(1/2) / (2*zeta(1/2)), where gamma is the Euler-Mascheroni constant A001620 and G is the Catalan constant A006752. - Vaclav Kotesovec, Feb 19 2020
Also equals (-32 - log(Pi)^2 + psi(0, 1/4)^2 + psi(1, 1/4) + 4*(psi(0, 1/4) * zeta'(1/2) + zeta''(1/2)) / zeta(1/2)) / 8, where psi(0, 1/4) = -A020777 and psi(1, 1/4) = A282823. - Vaclav Kotesovec, Feb 19 2020

A282824 Decimal expansion of Pi^2 - 8*K, where K is Catalan's constant.

Original entry on oeis.org

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

Offset: 1

Bruno Berselli, Mar 06 2017

			2.5418796476716064983976628804170782491205044129874135522813644192459406...

G. C. Greubel, Table of n, a(n) for n = 1..10000
Ernst D. Krupnikov and K. S. Kolbig, Some special cases of the generalized hypergeometric function _{q+1}F_q, J. Comp. Appl. Math. 78 (1997) 79-95
Eric Weisstein's World of Mathematics, Polygamma Function (formula 25).
Sheldon Yang, Some properties of Catalan's constant G, Internat. J. Math. Ed. Sci. Tech. 23 (4) (1992) 549-556

Cf. A000796, A006752, A247037, A173953/A173954, A282823.

SetDefaultRealField(RealField(100)); R:= RealField(); Pi(R)^2 - 8*Catalan(R); // G. C. Greubel, Aug 24 2018

RealDigits[Pi^2 - 8 Catalan, 10, 100][[1]]

Pi^2 - 8*Catalan \\ Charles R Greathouse IV, Jan 31 2018

zetahurwitz(2,3/4) \\ Charles R Greathouse IV, Jan 31 2018

Equals 16*A247037.
Equals Psi(1, 3/4), where Psi(r, x) is the Polygamma function of order r.
Because this equals Zeta(2, 3/4), with the Hurwitz Zeta function, this is the value of the series Sum_{k>=0} 1/(k + 3/4)^2 = 16*Sum_{k>=0} 1/(4*k+3)^2 with partial sums {A173953/(n+2) / A173954(n+2)}{n>=0}. - _Wolfdieter Lang, Nov 14 2017
A282823 - this = 16*A006752. - R. J. Mathar, Jun 07 2024

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A006752 Decimal expansion of Catalan's constant 1 - 1/9 + 1/25 - 1/49 + 1/81 - ...

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A173947 a(n) = numerator of (Zeta(2, 1/4) - Zeta(2, n+1/4)), where Zeta is the Hurwitz Zeta function.

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A332645 Decimal expansion of Sum_{n>=1} 1/z(n)^2 where z(n) is the imaginary part of the n-th nontrivial zero of the Riemann zeta function.

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A282824 Decimal expansion of Pi^2 - 8*K, where K is Catalan's constant.

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A375771 Decimal expansion of the absolute value of the second derivative of the digamma function at 1/4.

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