A332383 - OEIS

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A332383

a(n) is the X-coordinate of the n-th point of the dragon curve. Sequence A332384 gives Y-coordinates.

6

0, 1, 1, 0, 0, -1, -1, -2, -2, -3, -3, -2, -2, -3, -3, -4, -4, -5, -5, -4, -4, -3, -3, -2, -2, -3, -3, -2, -2, -3, -3, -4, -4, -5, -5, -4, -4, -3, -3, -2, -2, -1, -1, -2, -2, -1, -1, 0, 0, -1, -1, 0, 0, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 0, 0, -1, -1, 0, 0, 1, 1, 2

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,8

COMMENTS

To build the curve:

- start from the origin looking to the right,

- for k = 0, 1, ...:

- move forward to the next lattice point,

- if A014577(n) = 1 then turn 90 degrees to the left

otherwise turn 90 degrees to the right.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..8192

Rémy Sigrist, Colored representation of the first 2^18 points

Eric Weisstein's World of Mathematics, Dragon Curve

Wikipedia, Dragon curve

Index entries for sequences related to coordinates of 2D curves

FORMULA

For any k >= 0:

- a(2^(4*k)) = (-4)^k,

- a(2^(4*k+1)) = (-4)^k,

- a(2^(4*k+2)) = 0,

- a(2^(4*k+3)) = -2*(-4)^k.

MATHEMATICA

Re[Join[{0}, Accumulate[Nest[Join[#, Reverse[I #]] &, {1}, 7]]]] (* Vladimir Reshetnikov, Apr 14 2022 *)

PROG

(PARI) A014577(n)=1/2*(1+(-1)^(1/2*((n+1)/2^valuation(n+1, 2)-1)))

{ z=0; d=1; for (n=0, 71, print1 (real(z) ", "); z += d; d*=if (A014577(n), +I, -I)) }

CROSSREFS

See A332251 for a similar sequence.

Cf. A014577, A332384 (Y-coordinates).

Sequence in context: A076902 A287271 A290884 * A340327 A332249 A049113

Adjacent sequences: A332380 A332381 A332382 * A332384 A332385 A332386

KEYWORD

sign,look,base

AUTHOR

Rémy Sigrist, Feb 10 2020

STATUS

approved