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A332498 a(n) = y(w+1) where y(0) = 0 and y(k+1) = 2^(k+1)-1-y(k) (resp. y(k)) when d_k = 2 (resp. d_k <> 2) and Sum_{k=0..w} d_k*3^k is the ternary representation of n. Sequence A332497 gives corresponding x's. 2
0, 0, 1, 0, 0, 1, 3, 3, 2, 0, 0, 1, 0, 0, 1, 3, 3, 2, 7, 7, 6, 7, 7, 6, 4, 4, 5, 0, 0, 1, 0, 0, 1, 3, 3, 2, 0, 0, 1, 0, 0, 1, 3, 3, 2, 7, 7, 6, 7, 7, 6, 4, 4, 5, 15, 15, 14, 15, 15, 14, 12, 12, 13, 15, 15, 14, 15, 15, 14, 12, 12, 13, 8, 8, 9, 8, 8, 9, 11, 11 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..6560

Wikipedia, T-square (fractal)

FORMULA

a(n) = 0 iff n belongs to A005836.

EXAMPLE

For n = 42:

- the ternary representation of 42 is "1120",

- x(0) = 0,

- x(1) = x(0) = 0 (as d_0 = 0),

- x(2) = 2^2-1 - x(1) = 3 (as d_1 = 2),

- x(3) = x(2) = 3 (as d_2 = 1 <> 2),

- x(4) = x(3) = 3 (as d_3 = 1 <> 2),

- hence a(42) = 3.

PROG

(PARI) a(n) = { my (y=0, k=1); while (n, if (n%3==2, y=2^k-1-y); n\=3; k++); y }

CROSSREFS

Cf. A005836, A332497 (corresponding x's and additional comments).

Sequence in context: A271082 A053375 A117252 * A181407 A114187 A016037

Adjacent sequences:  A332495 A332496 A332497 * A332499 A332508 A332509

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, Feb 14 2020

STATUS

approved

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Last modified June 6 16:34 EDT 2020. Contains 334828 sequences. (Running on oeis4.)