A069986 Denominator of b(n) = binomial(2n,n)^3*(42n+5)/2^(12n+4).
16, 8192, 33554432, 17179869184, 562949953421312, 288230376151711744, 1180591620717411303424, 604462909807314587353088, 158456325028528675187087900672, 81129638414606681695789005144064, 332306998946228968225951765070086144
Offset: 0
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).
Programs
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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 *)
Formula
Sum_{n>=0} b(n) = 1/Pi (Ramanujan, 1914).