login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A069986 Denominator of b(n) = binomial(2n,n)^3*(42n+5)/2^(12n+4). 2
16, 8192, 33554432, 17179869184, 562949953421312, 288230376151711744, 1180591620717411303424, 604462909807314587353088, 158456325028528675187087900672, 81129638414606681695789005144064, 332306998946228968225951765070086144 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 0..277

Srinivasa Ramanujan, Modular equations and approximations to Pi, Quart. J. Math., Vol. 45 (1914), pp. 350-372. See p. 45, eq. (29).

FORMULA

Sum_{n>=0} b(n) = 1/Pi (Ramanujan, 1914).

MATHEMATICA

a[n_] := Denominator[Binomial[2 n, n]^3*(42 n + 5)/2^(12 n + 4)]; Array[a, 10, 0] (* Amiram Eldar, Apr 29 2022 *)

CROSSREFS

Cf. A049541, A069985 (numerators).

Sequence in context: A203390 A221085 A280845 * A265177 A151641 A265240

Adjacent sequences:  A069983 A069984 A069985 * A069987 A069988 A069989

KEYWORD

easy,frac,nonn

AUTHOR

Benoit Cloitre, May 01 2002

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 6 04:09 EDT 2022. Contains 357261 sequences. (Running on oeis4.)