The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A248725 Decimal expansion of Sum_{k>=1} 1/(8^k - 1). 6
 1, 6, 0, 9, 6, 6, 1, 8, 4, 3, 1, 5, 0, 6, 2, 3, 9, 6, 8, 0, 5, 3, 0, 2, 5, 6, 4, 1, 4, 3, 6, 4, 2, 8, 8, 5, 5, 5, 0, 7, 4, 3, 8, 5, 6, 0, 2, 5, 3, 2, 8, 3, 4, 6, 3, 6, 0, 8, 3, 5, 9, 1, 8, 6, 4, 7, 8, 2, 3, 9, 4, 0, 8, 5, 8, 0, 0, 6, 3, 6, 9, 1, 7, 7, 9, 2, 3, 4, 5, 3, 1, 0, 0, 9, 3, 2, 5, 4, 0, 2, 5, 2, 9, 6, 4 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS G. C. Greubel, Table of n, a(n) for n = 0..10000 FORMULA Equals Sum_{k>=1} d(k)/8^k, where d(k) is the number of divisors of k (A000005). - Amiram Eldar, Jun 22 2020 EXAMPLE 0.16096618431506239680530256414364288555074385602532834636083591864782394085800... MAPLE evalf(sum(1/(8^k-1), k=1..infinity), 120) # Vaclav Kotesovec, Oct 18 2014 MATHEMATICA x = 1/8; RealDigits[ Sum[ DivisorSigma[0, k] x^k, {k, 1000}], 10, 105][[1]] (* after an observation and the formula of Amarnath Murthy, see A073668 *) PROG (PARI) suminf(k=1, 1/(8^k-1)) \\ Michel Marcus, Oct 18 2014 CROSSREFS Cf. A000005, A065442, A073668, A214369, A248721, A248722, A248723, A248724, A248726. Sequence in context: A112246 A189037 A153201 * A118178 A021168 A147709 Adjacent sequences:  A248722 A248723 A248724 * A248726 A248727 A248728 KEYWORD nonn,cons AUTHOR Robert G. Wilson v, Oct 12 2014 STATUS approved

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

Last modified September 22 10:34 EDT 2020. Contains 337289 sequences. (Running on oeis4.)