login
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
OFFSET
0,1
LINKS
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 * A366361 A265177 A151641
KEYWORD
easy,frac,nonn
AUTHOR
Benoit Cloitre, May 01 2002
STATUS
approved