A335359 - OEIS

A335359

a(n) is the Y-coordinate of the n-th point of the Koch curve; sequence A335358 gives X-coordinates.

0, 0, 1, 0, 0, 1, 2, 2, 3, 2, 2, 1, 0, 0, 1, 0, 0, 1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 6, 6, 7, 8, 8, 9, 8, 8, 7, 6, 6, 7, 6, 6, 5, 4, 4, 3, 2, 2, 1, 0, 0, 1, 0, 0, 1, 2, 2, 3, 2, 2, 1, 0, 0, 1, 0, 0, 1, 2, 2, 3, 4, 4, 5, 6, 6, 7, 6, 6, 7, 8, 8, 9, 10, 10, 11, 12

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OFFSET

0,7

COMMENTS

Coordinates are given on a hexagonal lattice with X-axis and Y-axis as follows:

0 ---- X

LINKS

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

Wikipedia, Koch snowflake

Index entries for sequences related to coordinates of 2D curves

FORMULA

a(n) = 0 iff n belongs to A332206.

EXAMPLE

The Koch curve starts (on a hexagonal lattice) as follows:

. . . . . . + . . . . . .

/8\

. . . . +---+ +---+ . . . .

6\ 7 9 /10

. . . + . + . + . + . . .

/2\ /5 \ / \

. +---+ +---+ . . +---+ +---+ .

0 1 3 4 12 13 15 16

Hence, a(6) = a(7) = a(9) = a(10) = 2.

PROG

(PARI) { hex = [1, I, I-1, -1, -I, 1-I]; z=0; for (n=0, 84, print1 (imag(z)", "); q=digits(n, 4); d=sum(k=1, #q, if (q[k]==1, +1, q[k]==2, -1, 0)); z+=hex[1+d%#hex]) }

CROSSREFS

Cf. A065359, A332206, A335358.

Sequence in context: A156747 A318958 A194827 * A332205 A219237 A138774

Adjacent sequences: A335356 A335357 A335358 * A335360 A335361 A335362

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, Jun 03 2020

STATUS

approved