cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A329591 Decimal expansion of sqrt(34 + 2*sqrt(17))/4 = sqrt(8 + A222132)/2.

Original entry on oeis.org

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

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Author

Wolfdieter Lang, Feb 17 2020

Keywords

Comments

The present cp := sqrt(34 + 2*sqrt(17))/4 is used, together with cm := sqrt(34 - 2*sqrt(17))/4 = sqrt(9 - A222132)/2 = A329592, for the roots of the integer polynomial P(4, x) := x^4 + x^3 - 6*x^2 - x + 1 which are x1 = 4 + cp - 2*cp^2, x2 = 4 - cp - 2*cp^2, x3 = 4 + cm - 2*cm^2, and x4 = 4 - cm - 2*cm^2. The approximate values of these zeros are 0.344150732, -2.905703544, 2.049481177, and -0.4879283650, respectively.
In the power basis of cp (denoted by (...)) and cm (denoted by [...]) the roots of P(4, x) are therefore: (4, +1, -2), (4, -1, -2), [4, +1, -2] and [4, -1, -2], respectively.

Examples

			1.62492713781332594517011169187886610389245001466924916684547590815419...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[Sqrt[34 + 2*Sqrt[17]]/4, 10, 100][[1]] (* Amiram Eldar, Feb 17 2020 *)

Formula

cp := sqrt(34 + 2*sqrt(17))/4 = sqrt(8 + w(17))/2, where w(17) = (1 - sqrt(17))/2 = A222132.