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A337132 a(n) is the number of squares at distance n from the central square of a Vicsek fractal. 2
1, 4, 4, 4, 12, 4, 4, 12, 4, 4, 12, 12, 12, 36, 4, 4, 12, 4, 4, 12, 12, 12, 36, 4, 4, 12, 4, 4, 12, 12, 12, 36, 12, 12, 36, 12, 12, 36, 36, 36, 108, 4, 4, 12, 4, 4, 12, 12, 12, 36, 4, 4, 12, 4, 4, 12, 12, 12, 36, 12, 12, 36, 12, 12, 36, 36, 36, 108, 4, 4, 12 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

For symmetry reasons, a(n) is a multiple of 4 for any n > 0.

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..6561

Rémy Sigrist, Illustration of initial terms

Rémy Sigrist, PARI program for A337132

Wikipedia, Vicsek fractal

FORMULA

a(n) = 4 iff n belongs to A153775.

PROG

(PARI) See Links section.

CROSSREFS

See A337018 for similar sequences.

Cf. A153775.

Sequence in context: A220931 A219578 A219373 * A151906 A151896 A267191

Adjacent sequences:  A337129 A337130 A337131 * A337133 A337134 A337135

KEYWORD

nonn

AUTHOR

Rémy Sigrist, Nov 21 2020

STATUS

approved

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Last modified October 27 09:46 EDT 2021. Contains 348273 sequences. (Running on oeis4.)