A388622 Decimal expansion of 4 - 2*sqrt(2).

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

Offset

1,3

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Simon Plouffe, Numbers in the base e^Pi, 2025.

Index entries for algebraic numbers, degree 2.

Formula

Empirical: Equals Sum_{k>=0} A134746(k) / exp(k*Pi).

Equals 2*A101465 = 1/A201488. - Hugo Pfoertner, Sep 21 2025

Minimal polynomial: x^2 - 8*x + 8. - Amiram Eldar, May 31 2026

Example

1.17157287525380990239662255158060384...

Mathematica

First[RealDigits[4 - 2*Sqrt[2], 10, 100]] (* Paolo Xausa, Sep 21 2025 *)

Prog

(PARI) 4 - 2*sqrt(2)

Crossrefs

Cf. A101465, A134746, A201488.

Essentially the same as A157259.

Sequence in context: A379799 A351738 A178757 * A376841 A195369 A367710

Adjacent sequences: A388619 A388620 A388621 * A388623 A388624 A388625

Keyword

nonn,cons,easy

Author

Simon Plouffe, Sep 18 2025

Status

approved