A087689 Numerators of successive partial sums of sum(1/(2^n-1)).

1, 4, 31, 54, 1709, 15536, 1982837, 33790906, 2469747943, 27183776108, 55662119048981, 241239187192714, 1976140351325516359, 28325754514689966424, 4277270178238249409079, 659561325495450888962794, 86449773005982522786719469901, 2111849468951772510442846393460

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..103

Eric Weisstein's World of Mathematics, Erdős-Borwein Constant

Example

a(3)=31 because 1/1 + 1/3 + 1/7 = 31/21.

Maple

a:= n -> numer(add(1/(2^j-1), j=1..n)):
seq(a(n), n=1..18); # Robert Israel, Dec 28 2012

Mathematica

Numerator[Accumulate[1/(2^Range[20]-1)]] (* Harvey P. Dale, Dec 28 2012 *)

Prog

(PARI) a(n) = numerator(sum(k=1, n, 1/(2^k-1))); \\ Michel Marcus, Dec 20 2025

Crossrefs

Cf. A000225, A087690.

Cf. A065442.

Sequence in context: A371034 A216302 A070522 * A330788 A374720 A210377

Adjacent sequences: A087686 A087687 A087688 * A087690 A087691 A087692

Keyword

frac,nonn

Author

Keenan Pepper, Sep 27 2003

Extensions

More terms from Ray Chandler, Oct 26 2003

Status

approved