A157215 Decimal expansion of 18 - 5*sqrt(2).

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

Offset

2,3

Comments

Limit_{n -> oo} b(n)/b(n-1) = (18+5*sqrt(2))/(18-5*sqrt(2)) for n mod 3 = {1, 2}, b = A129544.

Limit_{n -> oo} b(n)/b(n-1) = (18+5*sqrt(2))/(18-5*sqrt(2)) for n mod 3 = {0, 2}, b = A157213.

Links

G. C. Greubel, Table of n, a(n) for n = 2..5001

Index entries for algebraic numbers, degree 2.

Formula

Minimal polynomial: x^2 - 36*x + 274. - Amiram Eldar, May 01 2026

Example

10.92893218813452475599155637895150960715164062311525...

Mathematica

RealDigits[18 - 5*Sqrt[2], 10, 50][[1]] (* G. C. Greubel, Nov 28 2017 *)

Prog

(PARI) 18 - 5*sqrt(2) \\ G. C. Greubel, Nov 28 2017
(Magma) [18 - 5*Sqrt(2)]; // G. C. Greubel, Nov 28 2017

Crossrefs

Cf. A129544, A157213, A157214 (decimal expansion of 18+5*sqrt(2)), A157216 (decimal expansion of (18-5*sqrt(2))/(18+5*sqrt(2))).

Sequence in context: A241560 A309821 A073007 * A021919 A078127 A383188

Adjacent sequences: A157212 A157213 A157214 * A157216 A157217 A157218

Keyword

cons,nonn

Author

Klaus Brockhaus, Feb 25 2009

Status

approved