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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A065446 Decimal expansion of Product_{k>=1} (1-1/2^k)^(-1). 21
 3, 4, 6, 2, 7, 4, 6, 6, 1, 9, 4, 5, 5, 0, 6, 3, 6, 1, 1, 5, 3, 7, 9, 5, 7, 3, 4, 2, 9, 2, 4, 4, 3, 1, 1, 6, 4, 5, 4, 0, 7, 5, 7, 9, 0, 2, 9, 0, 4, 4, 3, 8, 3, 9, 1, 3, 2, 9, 3, 5, 3, 0, 3, 1, 7, 5, 8, 9, 1, 5, 4, 3, 9, 7, 4, 0, 4, 2, 0, 6, 4, 5, 6, 8, 7, 9, 2, 7, 7, 4, 0, 2, 9, 4, 8, 4, 3, 3, 5, 3, 5, 0, 8, 8, 0 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES Steven R. Finch, Mathematical Constants, Cambridge, 2003, pp. 354-361. LINKS Harry J. Smith, Table of n, a(n) for n=1..2000 Steven R. Finch, Digital Search Tree Constants [Broken link] Steven R. Finch, Digital Search Tree Constants [From the Wayback machine] Igor Pak, Greta Panova, and Damir Yeliussizov, On the largest Kronecker and Littlewood-Richardson coefficients, arXiv:1804.04693 [math.CO], 2018. [p. 13] Jonathan Sondow and Eric W. Weisstein, MathWorld: Wallis Formula. FORMULA Equals Sum_{n>=0} 1/A002884(n)*Product_{j=1..n} 2^n/(2^n-1). - Geoffrey Critzer, Jun 30 2017 Equals 1/QPochhammer(1/2, 1/2)_{infinity}. - G. C. Greubel, Jan 18 2018 Equals 1 + Sum_{n>=1} 2^(n*(n-1)/2)/((2-1)*(2^2-1)*...*(2^n-1)). - Robert FERREOL, Feb 22 2020 Equals 1 / A048651 (constant). - Hugo Pfoertner, Nov 28 2020 Equals Sum_{n>=0} A000041(n)/2^n. - Amiram Eldar, Jan 19 2021 EXAMPLE 3.46274661945506361153795734292443116454075790290... MAPLE evalf(1+sum(2^(n*(n-1)/2)/product(2^k-1, k=1..n), n=1..infinity), 120); # Robert FERREOL, Feb 22 2020 MATHEMATICA N[ Product[ 1/(1 - 1/2^k), {k, 1, Infinity} ], 500 ] RealDigits[1/QPochhammer[1/2, 1/2], 10, 100][[1]] (* Vaclav Kotesovec, Jun 22 2014 *) PROG (PARI) { default(realprecision, 2080); x=prodinf(k=1, 1/(1 - 1/2^k)); for (n=1, 2000, d=floor(x); x=(x-d)*10; write("b065446.txt", n, " ", d)) } \\ Harry J. Smith, Oct 19 2009 (PARI) prodinf(k=1, 1/(1-1/2^k)) \\ Michel Marcus, Feb 22 2020 CROSSREFS Cf. A000041, A002884, A048651, A048652, A006099. Sequence in context: A066977 A007551 A161012 * A159962 A214871 A055173 Adjacent sequences: A065443 A065444 A065445 * A065447 A065448 A065449 KEYWORD nonn,cons AUTHOR N. J. A. Sloane, Nov 18 2001 EXTENSIONS More terms from Robert G. Wilson v, Nov 19 2001 Further terms from Vladeta Jovovic, Dec 01 2001 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.

Last modified September 24 14:54 EDT 2023. Contains 365579 sequences. (Running on oeis4.)