A258715 Decimal expansion of 2*Sum_{k>=0} 1/Product_{i=0..k} (2^(2^i) - 1).

2, 7, 1, 1, 2, 8, 5, 4, 0, 5, 7, 0, 9, 6, 3, 3, 4, 4, 6, 6, 6, 6, 5, 2, 5, 4, 2, 9, 1, 8, 1, 4, 7, 9, 1, 0, 4, 6, 7, 9, 7, 6, 5, 8, 7, 7, 1, 9, 8, 9, 7, 5, 4, 5, 6, 9, 3, 7, 9, 5, 7, 1, 7, 0, 6, 7, 9, 5, 0, 1, 8, 9, 9, 9, 5, 5, 4, 4, 2, 8

Offset

1,1

Links

Table of n, a(n) for n=1..80.

Formula

From Amiram Eldar, Feb 19 2024: (Start)

Equals 2 * A258714.

Equals 2/A215016 - 3. (End)

Example

2.7112854057096334466665254291814791046797658771989754...

Mathematica

RealDigits[2/NProduct[1 - 1/2^(2^k), {k, 0, Infinity}, WorkingPrecision -> 120] - 3][[1]] (* Amiram Eldar, Feb 19 2024 *)

Prog

(PARI) 2/prodinf(k = 0, 1 - 1/2^(2^k)) - 3 \\ Amiram Eldar, Feb 19 2024

Crossrefs

Cf. A215016, A258714, A258716.

Sequence in context: A084794 A116691 A225592 * A011340 A081705 A371748

Adjacent sequences: A258712 A258713 A258714 * A258716 A258717 A258718

Keyword

nonn,cons

Author

N. J. A. Sloane, Jun 15 2015

Status

approved