0,2

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

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

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

(PARI) See Links section.

See A337018 for similar sequences.

Cf. A153775.

Sequence in context: A220931 A219578 A219373 * A151906 A151896 A267191

Adjacent sequences: A337129 A337130 A337131 * A337133 A337134 A337135

nonn

Rémy Sigrist, Nov 21 2020

approved