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A332250 a(n) is the Y-coordinate of the n-th point of the quadratic Koch curve. Sequence A332249 gives X-coordinates. 2
0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 2, 2, 3, 3, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 12, 12, 11, 11, 10, 10, 9, 9, 10, 10, 9, 9, 8, 8, 7, 7, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,9

COMMENTS

This sequence is the imaginary part of {f(n)} defined as:

- f(0) = 0,

- f(n+1) = f(n) + i^t(n)

  where t(n) is the number of 1's minus the number of 3's

             in the base 5 representation of n

    and i denotes the imaginary unit.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..15625

Index entries for sequences related to coordinates of 2D curves

FORMULA

a(5^k-m) = a(m) for any k >= 0 and m = 0..5^k.

PROG

(PARI) { k = [0, 1, 0, -1, 0]; z=0; for (n=0, 80, print1 (imag(z) ", "); z += I^vecsum(apply(d -> k[1+d], digits(n, #k)))) }

CROSSREFS

Cf. A332249 (X-coordinates and additional comments).

Sequence in context: A106747 A083447 A252489 * A059998 A234475 A329907

Adjacent sequences:  A332247 A332248 A332249 * A332251 A332252 A332253

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, Feb 08 2020

STATUS

approved

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Last modified April 9 19:36 EDT 2020. Contains 333362 sequences. (Running on oeis4.)