A298752 Decimal expansion of (1/2)*(1 + sqrt(-7 + 4*sqrt(5))).

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

Offset

1,3

Comments

The positive zero of x^2 - x + 2- sqrt(5).

Links

Clark Kimberling, Table of n, a(n) for n = 1..10000

Index entries for algebraic numbers, degree 4.

Formula

Minimal polynomial: x^4 - 2*x^3 + 5*x^2 - 4*x - 1. - Amiram Eldar, May 29 2026

Example

1.1971857553764202492...

Mathematica

r = (1/2)*(1 + Sqrt[-7 + 4 Sqrt[5]]);
RealDigits[N[r, 100], 10][[1]]

Prog

(PARI) (1+sqrt(-7+4*sqrt(5)))/2 \\ Charles R Greathouse IV, May 18 2026

Crossrefs

Cf. A298749, A298750, A298751.

Sequence in context: A393891 A254249 A393374 * A154396 A380795 A069611

Adjacent sequences: A298749 A298750 A298751 * A298753 A298754 A298755

Keyword

nonn,easy,cons,changed

Author

Clark Kimberling, Feb 13 2018

Status

approved